invariable largeness, always superior to that of our herrings of the Channel, of which the small dimensions are equally constant." Now, he said, it was true that considerable shoals of large herrings do appear on the Norway coast in the winter and spring; but the author seems not to have been aware that there is always in summer considerable shoals and a large fishery of small herrings, generally of a superior quality, but of a smaller size on the average than those caught in the English Channel (La Manche) or on the Scottish coasts; and he exhibited a specimen of each size, the one a giant of 13 inches, and the other a dwarf of about 9 inches, each with the ova fully developed, and said that any number of each size could be obtained. He alluded to the statement in the same work as to the exceedingly deciduous nature of the scales of the herrings, and said that this was an exaggeration, as was evident even from the specimens he produced, which were covered with their scales. It is stated in this work, that the herring spawns apparently indiscriminately, without selecting any position, even in the middle of the sea-" au milieu de la mer." But this is not the case; for Mr Mitchell had ascertained that the herring always selects rocky, stony, or gravelly ground, on which to deposit its spawn. He would also point out that at page 62, vol. xx., it is said, "c'est pendant l'hiver qu'ils appairrissent sur les côtes d'Europe." Now, it is well known that great shoals of herrings approach the coasts of Europe in summer and autumn, and are fished then, as already stated, in great quantities.

II. Observations on British Zoophytes and Protozoa. By T. STRETHILL WRIGHT, M.D.

1. On the Reproductive Elements of the Rhizopoda. Plate IX. We have, as far as I am aware, no definite observations as to the reproductive elements of the Rhizopods. All who are accustomed to the observation of minute marine life know that these creatures increase with great rapidity; but how they increase is at present a mystery.

Professor Carpenter* has recorded and figured a peculiar *Phil. Trans., vol. cxlvi. p. 212.

state of the sarcode as occurring in spirit specimens of Orbitolite, which appeared to be broken up into little spherules, though still retaining the structure of unchanged sarcode. He also states that similar spherules are figured by Ehrenberg in several of the cells of Sorites orbiculus, and by Schultze in the chambers of Rotalia. Dr Carpenter is inclined to believe that these bodies are gemmules. I have repeatedly noticed bodies, apparently similar to those figured by Carpenter, in Gromia; but I have considered them to be of the same nature as the coloured spherules which are found within the endoderm of the Hydroid Zoophytes.

Besides these spherules, however, Dr Carpenter has met with other bodies, apparently imbedded in the sarcode, which he considered might be gemmules in a later stage, or ova. These were of a deep-red colour, and exhibited various stages of binary division. He has also figured a third object, found in an imperfectly closed shell of Orbitolite, which, with his usual caution, he considered might possibly have been introduced from without.

It is under these circumstances that I bring forward the following observations.

With regard to the female element, it will be necessary first to ascertain the essential characters of an ovum. Professor Allan Thomson* defines it as "a detached spheroidal mass of organised substance, of variable size, enclosed in a vesicular membrane, and containing, in the earlier periods of its existence, an internal cell or nucleus." But the presence of a nucleus is not essential to the constitution of an ovum; for in the ova of Chrysaora hyoscella and some of the Ctenophora (Beroë) it cannot be detected at any stage. The ova of these animals may be defined as "detached masses of highly refractive substance." Such appears to be the simplest definition of an ovum-a definition which will apply also to the first stage of the ovum of Rhizostoma as figured by Professor Thomson,t where he shows, first, the "primitive ovum" destitute of germinal vesicle and spot; secondly, the appearance of the germinal vesicle; thirdly,

* Cyclopædia of Anat. and Phys., vol. v. p. 128.

† Op. Cit. p. 128.

the advent of the macula within the vesicle; and, lastly the formation of the enclosing membrane.

On examining a great number of specimens of Gromia, Miliolina, Rotalina, and Orbulina, I have repeatedly discovered bodies which correspond in all respects with the

primitive ovum" defined above. They consist of transparent spheres or ovoids formed of a finely molecular substance, but in which the molecules are masked or rendered indistinct by the highly refractive matter in which they are imbedded. No germinal vesicle or spot appears in the living specimens. It may be masked in a similar manner to the molecular structure; but in a specimen of Truncatulina (Pl. IX. fig. 6) which has been hardened in spirit, decalcified by dilute nitric acid, and mounted with strong heat in Canada balsam, four of the segments or zooids contain each an ovum which shows a germinal vesicle and spot with the utmost distinctness, while the rest present the usual appearance of granular, low-refracting sarcode.*

I have not been able to trace the development of the ova of Rhizopods. Bodies similar to those I have considered ova in Gromia are found attached to Algæ in vessels where that animal abounds. The ova of Gromia are very small; and young Gromias slightly larger than the ova also occur. In Gromia, therefore, the ova may be at once transformed into young, and directly acquire an envelope. Such is the mode of development in the ova of most of the Hydroidæ, which are transformed into planuloid larvæ without undergoing fissure. In Orbulina, however, the ovum is of very large size, and consists of a colourless spherule of sarcode enclosed in a membraneous test and covered by a thin glairy layer. Here the sarcode presents traces of fissure, though these are lost when it is pressed out of its envelope. In both this genus and Truncatulina it is impossible that the fullsized ova can obtain exit from the animal, except by the destruction of the chambers of solid shell in which they are enclosed. In the case of Truncatulina, moreover, the ova are at least ten times as large as the primordial segment or

* I shall be happy to lend this preparation to any gentleman who may take an interest in it.

zooid of the adult. It is therefore probable that the ova of these genera undergo a "polymorphic" development of many months' duration, similar to that described by Carter as occurring in Amaba verrucosa,* and that each ovum becomes transformed into numerous Amoeboid zooids, which escape through the openings of the shell and form the primordial segments of future Rhizopods.

With regard to the male element, I have only one observation to record. Amongst a large number of dark-brown Gromias which I have possessed for many months, one appeared filled as to its upper part with a milky matter, which, when pressed out, proved to be a congeries of cells and large active molecules, such as are obtained from the sperm-sacs of Hydra viridis. I was not able to make out the tails of the spermatozoa; but there could be no mistaking the characteristic shape and movements of the cells and molecules. The sarcode of the body in Rhizopods is itself finely molecular in structure, and, when crushed, exhibits slight molecular movements; but these movements are altogether different from those of the objects which I am persuaded are the spermatozoa of Gromia.

Since the foregoing paper was sent to the press, I have received the April Number of the "Annals," in which Schultze's discovery of living young in the chambers of Rotalia is brought before the readers of this Journal. Professor Williamson, in his "Treatise on Recent Foraminifera" (Ray Soc. Publ.) states, in regard to his Spirillina perforata, "He (Professor Ehrenberg) assigns to it the trivial name of vivipara, owing to the circumstance that just within. the septal orifice of his specimen he found two small spiral shells, which had obviously found their way there by accident; from this unimportant circumstance, he concluded that the shell was viviparous." S. perforata is plentiful in the Firth of Forth, on Fucus serratus. Immediately after reading Schultze's paper, I examined a quantity of the seaweed, and found two large specimens of S. perforata surrounded by a multitude of very small ones. In one of the large specimens three small living Spirillinæ existed. Eh

* Ann. Nat. Hist., ser. 2, vol. xx. p. 37.

renberg was doubtless right in considering this animal viviparous; but it remains to be determined whether the young are produced by gemmation or ovulation. In Spirillina foliacea I have found the highly refractive bodies I have above described as "primitive ova."

Explanation of Plate IX.

Fig. 6. Specimen of Truncatulina, decalcified; a, membranous basis of shell; b, sarcode; c, ovum, with germinal vesicle and spot; d, segment or zooid destitute of ovum.

2. On the Reproduction of Ophryodendron.

Ophryodendron abietinum, which I have figured in various attitudes in Pl. X., has been noticed elsewhere by Claparède and Lachmann* and myself† several years since; but it was not until the spring of the present year that I was able to discover its mode of reproduction. The animal presents the appearance of an oblong sac filled with homogeneous and finely molecular matter, and is found attached to the corallum of Sertularia pumila. From one end of the body or sac arises a proboscis, generally appearing as a short and closely-wrinkled club, but capable of being produced to a remarkable distance as a glassy ribbon surmounted by numerous twining tentacles. The sac usually shows no trace of a nucleus or contractile vesicle, nor are its contents differentiated into an external and internal tissue (ectosarc and endosarc), as in Actinophrys and others of the class. ("Acinétiens") into which it has been introduced. The structure of the proboscis differs from that of the sac in the development within it, of a clear and highly refractive tissue, corresponding to the muscular element in the branches of Zoothamnium, and in the more directly contractile pedicle of Zooteirea. In the proboscis of Ophryodendron, as in the body of Epistylis, the contraction of the muscle throws its outer covering into close folds. The tentacles are formed of a continuation of the contractile tissue of the proboscis, and are covered to within a short distance of their tips by the integument. The proboscis, when extended, hangs

Etudes sur les Infusoires et les Rhizopodes, par Edouard Claparède et Johannes Lachmann.

† Edin. Phil. Journal, July 1859.