s Art. 8.— T. Kabiiraki : 



region, distinctly narrower in tlie tail, and very narrow along 

 either side of the body. The cells are not glandular, hut 

 perforated by the ducts of glandular cells which are deeply embed- 

 ded in the parenchyma below the dermal musculature. Besides, 

 there exist some similar cells here and there in scattered distribu- 

 tion, chiefly over the ventral surface of the body. By means of 

 the secretion the worm is able to adhere with surprising firmness 

 to a smooth surface, quite a strong jet of water being necessary 

 to displace it. 



Besides, the epidermis also holds in the tentacular and frontal 

 regions special cells, designated under the name of sensory cells, 

 which are provided with well developed cilia, but completely 

 devoid of rhabdites. In the case of Ect. limuli they show no 

 nuclei. As usual, the cells exhibit to a considerable extent a 

 fibrinous structure, the fibrillae appearing to stand in connexion 

 with nurofibrillae. Besides, any special sensory cells, demonstrat- 

 ed by BöiiMTG (5) in Pr. ulvae and Planaria gonocephala, could not 

 be brought under observation. 



Now as to the epidermis or epithelium of the Plathelminthes 

 in general. In some Triclads there can frequently be recognised 

 a special epidermis, in which no nuclei are present at all, much as 

 in the Trematodes and Gestodes. Some authors [Seidl (55), 

 Sabussow (51) and Böhmig] ol)served the case in the frontal sensory 

 part of the body in several species {Sorocelis stummeri, S. gracilis, 

 kS. laetea, S. sahicssoim, S. rosea, Planaria wytegrensis and 

 Procerodes ohllni). Especially it is of great interest that in the 

 hitherto known limulus-infesting Bdelloura- and Syncoelldkmi- 

 species no trace of nuclei could anywhere be detected in the 

 epidermis which is a homogeneous and ciliated layer, and is also 

 wholly devoid of rhabdites, except in one species of Bd. pi^opin- 

 qua. The nucleus containing parts are sunk into the parenchyma 

 immediately below the dermal musculature. In vertical sections, 

 it is impossible to distinguish cell-boundaries with ease, but in 

 tangential ones, polygonal spaces are apparent, which probably 

 represent the callular character. So far as my observations go, 

 similarity can be demonstrated in the frontal sensor}^ region only 



