crystals connected in series, and that this stringing together of the minute rods, and the parallel grouping of the strings, persisted even throughout a great number of chemical changes in the cellulose itself. For example, the rodlike structure of the micella was not affected when cellulose was treated with nitric acid and thus converted into guncotton.

These conclusions were brilliantly confirmed when the X-ray was applied to the investigation of fibres. In 1920 ramie, an almost pure form of cellulose, was discovered to produce an X-ray photograph of a kind previously observed only in case of crystals. For example, while noncrystallized, or socalled amorphous, substances produce simply a black blur on a Röntgen plate, crystals and crystalline bodies produce a number of alternating bright and dark curved lines called interference lines. The appearance and strength of these lines bear an intimate relation to the inner structure of the crystal- the so-called crystal grating. In case of ramie fibres, these interference rings were not, to be sure, complete, but fell into definite symmetrically arranged points or short segments of circles. Polanyi, who in 1921 made an exhaustive investigation of these Röntgen, four-point patterns, or fibre diagrams, showed that they appear only when the innumerable tiny crystals that form a crystalline substance all lie with their axes in the same direction, instead of in different directions. Such an arrangement of these crystalloids in parallels is characteristic of the structure of all fibres not only of ramie, but cotton, silk, wood fibre, and all similar substances of vegetable or animal origin, including hair, muscles, and

nerves.

But while natural cellulose in the form of ramie, cotton, flax, and other similar fibres, has all its crystallized

micelle lying with their axes parallel to the axis of the fibre itself, that is not true of artificial cellulose, mercerized cotton, and most kinds of artificial silk. The latter have their crystals lying pell-mell in all directions, and an X-ray photograph of them shows alternating dark and light lines in closed circles.

Very recently it has proved possible, by employing certain methods of drawing and tension when the cellulose is leaving the copper-ammoniac solution, to produce an artificial silk whose crystalline structure as shown by its X-ray photograph is the same as that of natural cellulose. In other words, its rodlike, crystalloid micellæ all have their axes lying in the same direction. The displacement, or jumbling-up out of their normal parallel order, of the crystals in ordinary artificial silk explains why this substance reacts so much more readily to chemicals, and absorbs water and colors so much more quickly, than natural fibres. Its component crystals lie in all directions, leaving interstices and exposing a larger surface to foreign ingredients like pigments and moisture. On the other hand, the end-to-end arrangement of the micellæ in parallel lines that exists in natural fibres is easy to understand, for it is necessary, not only for the upward growth of the plant, but in order to give the plant greater resistance to wind, weather, and other external influences.

While the origin of the crystalloid structures now assumed to make up every fibre is not definitely known, it is very probable that they do not exist in the young plant or animal from the beginning, but are developed from an amorphous jelly. Young asparagus, for example, and the chitin of insects in the chrysalis state, are still structureless, and consist of an incompact, watery substance that is later converted

into a firm crystalline composition. We may infer that drawing and tension play the same part in the formation of the fibre here that they do in the latest processes of producing artificial silk. Drawn-metal wire, which likewise consists of minute crystalline rods and consequently produces the same Röntgen diagrams as natural cellulose, gives us a hint to this effect, and confirms the inference that vegetable fibres are crystallized from some amorphous material.

This assumption has been strengthened by the results of recent investigations in natural silk-fibrine and chitin, which play the same part in the animal structure that cellulose does in the vegetable structure. In all these different organic compounds, both vegetable and animal, an identical crystalline substance has been discovered embedded in certain adhesive materials which chemists have for a long time designated as mucilages, or semicellulose, without knowing their exact constitution. Unless there were some such intermediate substance, cellulose itself would not possess sufficient resistance to wind-pressure and similar forces to perform its functions in plant and animal existence. For if the tiny crystalline rods were in direct contact, their size and shape would be easily modified by external accident and the strength of the cellulose fibre would be seriously weakened.

This binder or cement in cellulose is much more easily attacked by chemicals than the crystals themselves. Every laundryman knows how quickly textile fibres are affected by mineral acids, which weaken them so that they will rub to pieces between the fingers. Chemists have hitherto called the product resulting from the action. of such acids upon cellulose hydrocellulose, without being able to describe exactly what the chemical reaction

producing it was. Investigations show that this product consists mostly of unchanged or very slightly changed cellulose. X-ray photographs show that hydrocellulose has practically the same Röntgen diagram as ordinary cellulose. We are thus led to infer that acids do not affect the tiny crystalline rods or micella themselves, but only the binder between them, and that their effect is simply to allow these rods to fall apart.

This isolation of the crystalline bodies is important in its bearing upon other chemical transformations. We have already mentioned that when cotton is converted into guncotton, or nitrocellulose, the outer form of the fibres is not changed. All that occurs is an internal transformation, or pseudomorphosis, of the tiny crystalloids. That is, the chemical reaction occurs in each of these crystalloids individually, while it is kept in its original position by the binding substance. Very recent researches show that when cellulose absorbs water the latter is taken up by the binder between the micellæ, and not by the crystalloids themselves.

What we have said of the structural character of fibres, as consisting of minute micellæ, or rodlike crystalloids arranged parallel and end-to-end, which we can now assume to have been definitely demonstrated by the X-ray, fully explains two characteristics which distinguish cellulose from other organic substances its tensile strength and its chemical inertness. But when we extend our inquiries to the ultimate component of these crystalloid formations, to the primary parts of the micella, we immediately encounter new difficulties which have not yet been solved. We are practically certain that the ultimate constituents of the micella must be a grape-sugar residuum consisting of six atoms of carbon, ten atoms of hydrogen, and five atoms of oxygen. The presence of these grape-sugar or

glucose residua is inferred from the wellknown fact that both plant cellulose and starch, which is closely related to it, can be produced out of grape sugar and can again be converted into grape sugar. Cellulose and starch are easily converted into grape sugars with acids and ferments, by a process which we call hydrolysis, because it is associated with the incorporation of water in the cellulose molecule.

How many of these glucose residua are contained in the crystalloid cell, or micella, and how they are arranged with reference to each other, are not yet definitely known. To be sure, Polanyi has attempted to determine the constitution of the micella from X-ray photographs of cellulose. He has estimated the length of the three edges of these tiny, rodlike, orthorhombic, or possibly monoclinic crystals, and from that their cubical content, and has reached the conclusion that each micella has a volume of about six hundred and eighty quadrillionths of a cubic centimetre, which indicates that a small thimble would hold about fifteen hundred trillions of these little rods. Since we know how much space a single atom of carbon, hydrogen, or oxygen occupies, we can easily figure

out how many grape-sugar residua, with the chemical formula C.H1005, a single micella can contain. It works out practically four glucose groups to one cellulose crystal.

Unfortunately this astonishingly simple chemical solution, as derived from the X-ray photographs, is subject to some doubt. We are not perfectly certain whether the length of the edges of the rodlike micellæ may not be some multiple of the figure at which Polanyi arrived. If so, the number of glucose groups each one contains would be correspondingly increased. In any

case, the Röntgen method has not shown us definitely the molecular weight and the molecular size of the cellulose micella. The only way in which we can solve that problem beyond question will be by chemical analysis, probably by a procedure similar to that through which the constitution of albumin was so cleverly determined.

Provisionally, however, we are in possession of one interesting fact. Cellulose and other fibre materials do not consist, as chemists have hitherto assumed, of large and complex molecular combinations, but of relatively small and simple molecular groups.

TO-DAY I met upon the street my former German boy,' the pearl of boys. One day, shortly after I first came to China, he suddenly turned up in my kitchen. My old boy told me that he himself had been suddenly called back to Shantung by the death of his father. As a matter of fact, he had got a better job, for I saw him two days later washing the windows of a neighbor's house, and he gave me a cheerful bow. He explained that his friend Lu, who had been called Fritz by his former master, had come to take his place. I was a greenhorn and did not know that this was the invariable procedure in China, and was doubtful as to what I should do.

In the Celestial Kingdom death is a servant's conventional excuse for leaving a place or taking a vacation. Whenever a boy wants a little time off he kills his father or his mother. My present boy is not quite such a chronic mourner as most of them, especially since the first time he reported a new baby in his family as an excuse for a short absence and I gave him some of my husband's discarded linen to make clothes for it. Since then he has always reported new arrivals instead of departures when he wants a short vacation. I have figured out that these occur every three or four months, and wonder if he is a polygamist.

My husband's Chinese laboratory assistant has had a regular epidemic in his family. Death has followed death

1 From Vossische Zeitung (Berlin Liberal daily), April 16

with appalling frequency. But after every funeral the young man turns up at the Institute as blithe and merry as ever. The Chinese stenographer has had equally impressive reasons for pondering on our common mortality. He recently informed my husband, in great distress, that his last child had just died and that he must go to Tientsin to the funeral. I'll wager, though, that inside of a few months another child of his will need to be conducted to its last resting-place. Since death and funeral rites do not occur at the same time in China, but the latter ceremonies are held by the priests several months after the soul has left the body, these events have the advantage of making an excuse for two distinct holidays.

But to come back to Lu. I had no reason to regret the exchange. He had learned to cook at Tsingtau, where he had worked for a long time in the family of a first lieutenant. He never tired of singing the praises of the good man and his wife, and spoke German with remarkable fluency. It is a striking fact that the average Chinese servant here learns Russian and German perfectly, but never gets beyond pidgin in speaking English.

Lu had copied his etiquette from the lieutenant's orderlies. His 'Zu Befehl, Herr Doktor,' and his 'Weiss schon Bescheid, gnädige Frau,' with his hands precisely where his trouser-seams would have been if there were any in Chinese trousers, were impeccable.

One day when I went out into the

kitchen I discovered Lu- he had heard me coming-bathed in tears over his string beans. He rose respectfully when I entered, but his tragedy overpowered him, and seizing the wash cloth never too clean in a Chinese kitchen he wept aloud in it. In reply to my sympathetic questioning he informed me in a sob-broken voice: 'My wife has been kidnapped. [Suppressed sobs] They carried her to France [the French concession in Shanghai] and are detaining her there. They want a hundred-dollar ransom. [A new paroxysm of weeping] A friend has told me where she is. Can't I leave at noon to get her? [A new outburst of violent grief]'

I was almost overcome, half by sheer surprise, half by sympathy, but had the moral strength to say that I would consider the matter. Finally we agreed on a two hours' absence. Later I had every reason to believe that the whole comedy had been contrived merely so that my boy could get off for a wedding or a funeral.

My readers will understand that servants are allowed to leave the house only with the permission of their employers. To be sure, they slip away evenings after their work is done, and their masters and mistresses often wink at this practice. But instead of asking simply, 'May I have a few hours off?' a boy will invariably make up a long story to justify his excuse. If I were to show that I saw through his fibs, he would be insulted and leave me. He would have lost his face.

the furniture until it shines, waxes the chamber floors, and even sweeps out the corners! During the last half-hour before the guests arrive the whole house is in a fury of activity. Visitors must be impressed by the fine way in which his Tai-tai's house is kept.

If I have n't enough dishes, silver, or chairs, I need not worry about it. When my guests arrive the table is faultlessly set-flowers, silver, and porcelain are all there in abundance. Where do they come from? Mostly from our neighbors' houses naturally without their knowing anything about it. But it is a rare thing for a guest to recognize his own spoons, for although I never tell my boy who is coming, and the people I have invited never tell their servants where they are going, and the servants do not understand our language, all the boys know perfectly well that Mr. and Mrs. C will dine to-night with Dr. O

This secret news-service in China is wonderful. Even the diplomats profit by it. In some mysterious way a ricksha coolie knows before you leave the house just where you are going. During the winter, when there are 'at homes' almost daily, I need only get into my ricksha, without saying a word, to be carried directly to the place I wish. Not long ago, when we were going back on a visit to Germany through Siberia, my husband had arranged all his passport and letter-of-credit affairs except his Russian visé. He called a strange ricksha that happened to be standing in front of the house, and without his saying a word the puller took him directly to the Russian Embassy.

This custom of borrowing and lending things is a great convenience in a country where so many foreigners stay only a short time and do not wish to acquire a large stock of household goods. One time when we were giving a tea for Chinese students we were