STRUCTURE AND DEVETOPMENT OF COET,OPT,ANA. 43 



he reg'arded them to be a developmental stage of the muscle-fibres. 



Besides the elements mentioned above, the body parenchyme 

 contains a remakable body (PI. 4, fig. 10; co). It occurs in all parts of 

 the parenchyme, but especially in abundance in the ventral part of the 

 peripheral region of the body. It is generally oval, spheroidal or 

 sausage-shaped, and consists of granules which resemble very much, 

 but are somewhat coaser than, the granules occurring in the gland cells 

 of the epidermis, and present equally strong afifinity for eosin. Several 

 liattened nuclei are found among the granules and on the surface of the 

 body, indicating that it is made up of so many cells of a glandular 

 nature. The body shows no organic connection with any other tissue. 

 The nature of the body remains quite unknown to me. Abbott ('07) 

 has assumed that it may be a kind of parasitic organism. But, since it 

 reveals no other organization than that stated above, and further it is 

 distributed fairly regularly through the parenchyme, I am more inclined 

 to regard it to be a kind of reserve material. 



There remains to be described the nervous system. Concerning 

 the nervous system of the Ctenophora in general, very little is known as 

 yet. The results of the investigations of previous workers remain not 

 only very incomplete but also conflicting with one another. Apart, for 

 the present, from the old works such as Eimer's, we have thus far in 

 this field works by Chun ('80), Hertwig ('80), Samassa ('92) and 

 Bethe ('95), which may be outlined as follows : — Chun, to begin with, 

 has regarded the aboral sense-organ and the ciliated grooves that connect 

 the organ to each rib to represent the nervous system, and has termed 

 the former " Centralnervensystem ", and the latter " Nerven "; he has 

 denied the existence of ordinary nervous system in the Ctenophora. 

 Hertwig, on the contrary, has maintained the presence of two kinds of 

 nerve-plexuses, one in the subepithelial and the other in the mesodermal 

 region of the body. Against this opinion of Hertwig, Samassa has 

 stated that, the ctenophores have no special nervons system. Bethe, 

 somewhat later, reexamined Hertwig's preparations and accepted this 

 author's opinion; he further demonstrated by the methylene-blue vital 

 staining method, the existence of a nervous plexus in the subepithelial 

 region in a certain ctenophore. 



I could find nothing about the nervous system by examination 

 of ordinary sectioned preparations, and I employed the methylene- 

 blue vital staining method. Thus I could obtain, after many 

 unfruitful trials, some figures very likely to be of the nervous syster 



