1879.] Pliysio logy and Histology of Convoluta Schultzii. 455 



toplasm of tlie 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 

 amoeboid 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 

 Claparede, Metschnikoff,* Ulianin,t and Graff, J as to the absence of 

 any distinct alimentary canal. 



The development of the generative products is of interest. An 

 apparently ordinary mesoderm cell enlarges aud 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 amoeboid protoplasm of 

 the developing ovum. 



The "otolith" is transparent and strongly refracting. It is loosely 

 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 colour- 

 less 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 rom Bucht von Sebastopol." Moscow, 1870. 

 X " Kurze Ber. iiber fortgesetzte Turbellarienstudien," Zeitch. f. w. Zool., xxx, 

 Supp., p. 463. 



