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was purified by repeated solution and recrystallization in absolute alcohol. With PtCl, it yielded a precipitate, which was kindly analysed for me by Dr. Magnier de la Source, and found to be the platinochloride of methylamine: however, it is very probable that the volatile alkaloid was really more complex, but broke up in the distillation. The subject would repay the attention of a chemist. Trimethylamine has been obtained from many animal sources, and the production of this, or some nearly allied body, in such remarkable quantity by Convoluta seems to be a protective specialisation.

The ash of the Convoluta contains iodine, another analogy to the algæ.

As the Drosera, Dionæa, &c., which have attracted so much attention of late years, have received the striking name of Carnivorous Plants, these Planarians may not unfairly be called Vegetating Animals, for the one case is the precise reciprocal of the other. Not only does the Dionca imitate the carnivorous animal, and the Convoluta the ordinary green plant, but each tends to lose its own normal character. The tiny root of the Drosera and the half-blanched leaves of Pinguicula are paralleled by the absence of a distinct alimentary canal and the abstemious habits of the Planarian.

It still remains to ascertain the behaviour of other green animals, and I hope to begin with Hydra and Spongilla, * as soon as the season permits.

Part II.--Histology. The general characters of the animal have been already given by Schmidt, and I need only add that I have succeeded in making out the mouth, which lies, as usual in this genus, a little way behind the otolith. It is not a mere transverse slit, but is surrounded by a lip capable of slight protrusion, which evidently corresponds to the protrusible pharynx of higher Planarians. When feeling its way

the animal has a curious habit of sharply retracting the terminal point of the anterior ends of the body, the head thus becoming bilobed, with a central depression. Each lobe becomes a sort of temporary tentacle, and these

may be compared with the blunt permanent head lobes of allied forms. So too the animal “when extremely contracted” throws its smooth dorsal integument, not into irregular wrinkles, but into rounded papillæ, which remind one of the permanent dorsal papillæ of other Planarians.

I will first notice an interesting point in the histology of the ciliated ectoderm. In teased preparations, kept cold, the ciliated cells often become amoeboid, some of the cilia changing into slender finger-like or stout fusiform pseudopodia. These often retain their curvature parallel

* Sorby has suggested the probably partial vegetal mode of life of S. viridis, and resultant analogy to Dionæa. (“Quart. Journ. Micro. Sci.," 1875, p. 51.)

to the unaltered cilia, and I have even seen the finer pseudopodia contracting gently in time with the cilia of the same cell, thus establishing a complete gradation between the rhythmically contractile cilium and the amæboid pseudopodium through what is really a rhythmically contractile pseudopodium. Hæckel and others have accumulated many instances of the transformation of ciliary movement into amoboid and vice versâ, but I only know of one case in which the passage-form, the cilium-like pseudopodium, has been actually observed. Lankester, * speaking of developing spermatozoa of Tubifex, describes “very large active fusiform masses, exhibiting very rapid movements like a cilium, and possessing at the same time the character of a pseudopodium.” It is important that Lankester's passage-form occurred during the transformation of ameboid movement into ciliary, while I find exactly the same thing during the reverse change; and it is not improbable that such ciliary pseudopodia may transitorily occur in many cases.

Perhaps no animal structure has received more varied and contradictory interpretations than the rod-like bodies (Stäbchen, baguettes) of the Planarian integument. “Max Schultze holds them for end-organs of nerves, Leuckart and many others for nettle-capsules, Schneider for spicula amoris, Keferstein for mucous glands, Graff for more or less developed nematocysts.”+ Two distinct kinds of organ exist in Convoluta and other Rhabdocæles, and have been confused under the same name; first, the heap of coloured rod-shaped bodies, the original “Stäbchen” of Max Schultze, which furnish in Convoluta the yellow solution already referred to, and, secondly, large and long spindleshaped bodies, generally arranged singly, each containing a sharp brittle needle, of which the point lies close under the apex of the spindle. In a teased preparation they are generally empty, showing the tube in which the arrow lay, and with a little granular protoplasm hanging round the mouth like the smoke of the explosion. The dart is generally propelled for some little distance, but sometimes sticks in the mouth of the tube. Graff's view I is certainly the right one, that these are offensive weapons, but they are constructed on so distinct a plan from those of Calenterates, that they might better be called sagittocysts than nematocysts. True nematocysts have been described in some other Planarians.

Below the epidermis lie the circular and longitudinal muscles, and beneath them comes the layer of chlorophyll-containing cells. These are clear and semi-fluid, more or less irregular in shape, but becoming spherical when separated. The chlorophyll is not collected into granules as in the higher plants, nor into drops as in the green cells of Vortex viridis, but is diffused throughout the whole pro

*“Quart. Journ. Micro. Sci.,1870, p. 292.
+ Minot, “Studien an Turbellarien,” “Semper’s Archiv,” III, 4, 1877.
I“ Zeitsch. f. w. Zool.,” XIV, p. 421.

toplasm of the cell, which is thus very intensely coloured. One, or sometimes two, nuclei are present, besides an irregular heap of granules. It was very difficult to break up the cell completely, and so liberate the granules, but in one or two fortunate preparations treated with iodine, the blue coloration assumed by many of these granules proved that we have here an actual deposit of starch, quite like that which Sachs has shown to take place within the chlorophyll granules of the plant. These starch granules are many of them so minute as to show Brownian movements; the larger are quite amorphous, and consequently exhibit no polarisation.

Deeper than the green layer, lie colourless granular nucleated cells, which may be spherical or branched. These yield with iodine the red-brown reaction of glycogen very conspicuously indeed. All the internal tissues of the animal are bathed in that abundant slimy protoplasm which has been so often adduced in evidence of the infusorian affinities of the lower Turbellaria. It exudes from all points of the body of a squeezed Convoluta in hyaline drops, which generally enclose a heap of cells of all sorts, and which often show amcboid movements. This semi-fluid protoplasm oozing through the loose cell meshes with every movement of the body may well serve instead of a special circulatory fluid. Digestion may also be effected by the amoeboid protoplasm, for it is easy to confirm the statements of Claparède, Metschnikoff,* Ulianin,t and Graff, I as to the absence of any distinct alimentary canal.

The development of the generative products is of interest. An apparently ordinary mesoderm cell enlarges and divides into an oval mass of about 12—16 segments. The granular protoplasm of these is gradually drawn out into the very long spermatozoa, and thus each testicular mass is transformed bodily into a bundle of neatly folded spermatic filaments. The ova are also developed by the division of a mesoderm cell. There are no separate vitellaria, but the yolk granules seem to arise in the finely granular ameboid protoplasm of the developing ovum.

The “otolith” is transparent and strongly refracting. It is loosel contained in a capsule and shaped like a plano-convex lens, but with the plane under surface very rugged. I can form no hypothesis as to its function. In some forms what appears to be a nucleus is present, and the body is probably a modified epithelial cell.

Everywhere imbedded in the mesoderm are numerous small colourless cells scarcely so big as a frog's red blood corpuscle. These are more or less pear-shaped, with a large central cavity; and lining one

Zoologischer Anzeiger," 1878, p. 387. + “Die Turbellarien vom Bucht von Sebastopol.” Moscow, 1870.

I “Kurze Ber. über fortgesetzte Turbeslarienstudien,” Zeitch. f. w. Zool., xxx, Supp., p. 463.

side of the interior of this cavity and parallel to the long axis of the cell, are a number of distinct transparent homogeneous filaments in. serted above and below into the ordinary granular protoplasm which constitutes the remainder of the cell. This division of the cell into a granular and a fibrillated portion is similar, as Dr. Malassez suggested to me, to that which obtains in the developing muscular cell of a tadpole's tail, and though also somewhat remotely, to the structure described by Lankester in the heart of Appendicularia.* In a teased preparation, some of these cells are easily found in a state of rapid rhythmical contraction, giving as many as 100—180 energetic beats per minute. The form of the cell alters with every pulsation, shortening and broadening like a contracting muscle. This change of form is simply impressed upon the cell body by the contraction of the internal fibres, and does not therefore truly correspond to that observed in a muscle. Some cells also of extreme curvature (for hardly any two are quite alike) bend sharply and return with a spring. The movements soon become slow and inco-ordinate, and waves can be seen passing along the separate fibres independently of each other. The movement stops altogether and the cell bursts, but the fibres resist for some time longer the destructive action of the water.

I have never been able to observe any rhythmical contraction, but at most a feeble quivering within the cell while in the body of the animal, nor to make out any trace of definite arrangement. Max Schultze has described how the alimentary canal of the higher Planarians swarms with Opaline, and it is possible that these so singular structures may be excessively modified parasitic Infusoria. In any case, the main histological interest lies in the fact that these pulsatile cells cannot be classified either with ciliary or amæboid, with plain or striated muscular cells, but present a distinct type of contractile structure.

In one of these bodies, which had come to rest in the characteristic curved pear-like form, the nucleus-like body, which is often to be seen at one side, was distinctly seen to be in motion. It slowly dived under the contractile filaments, and moved steadily towards the opposite side, displacing the fibres slightly as it pushed its way. When it had reached the middle the cell had straightened into a per. fectly symmetrical pear-shape, and by the time it had reached the opposite side the cell had curved to the same side. After a momentary pause it commenced to go back again, and the oscillation of this singular body along the transverse diameter of the cell, with the accompanying changes of form of the whole, continued with perfect steadiness for at least half an hour, enabling me to draw all the phases again and again. One whole oscillation occupied a little over a minute.

* “ Ann, and Mag. Nat. Hist.” 1873, p. 88. + Figures will be published in the " Archives de Zoologie Expérimentale."

I must express my warmest thanks to M. de Lacaze-Duthiers, in whose laboratories at Roscoff and Paris I have received the greatest hospitality. The chemical examination of the animal was conducted in the Laboratoire de Chimie Biologique, of M. le Professeur Gautier, to whom my best thanks are also due and tendered.

Presents, March 6, 1879. Transactions. Cambridge [U.S.]:-Museum of Comparative Zoology at Harvard

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The Society London :-Physical Society. Proceedings. Vol. II. Part 4. 8vo. 1878.

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18. roy. 8vo.

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Members, Extra-Licentiates, and Licentiates. 8vo. London 1879.

The College. St. Petersburg :-Physikalische Central Observatorium. Annalen,

herausgegeben von H. Wild. Jahrgang 1877. 4to. 1878. Repertorium für Meteorologie, von H. Wild. Band VI. Heft 1. 4to. 1878.

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The Author. Duncan (P.M.), F.R.S. On some Ophiuroidea from the Korean Seas. 8vo. London 1878.

The Author. Cassell's Natural History. Vol. II. roy. 8vo. London 1878.

Messrs. Cassell. Macdonald (Dugald.) The Heavenly Bodies: how they move and what moves them. 8vo. Montreal 1877.

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