NOTES ON PARASITES. 8i 



adipose tissue. The nucleus of the cell can usually be seen 

 on one side of the calcareous nodule. 



There remains one point of great interest in Bloch- 

 mann's paper, and that is that his researches render it 

 extremely probable that the flame cells (Fig. I. /^) of the 

 excretory system are derived from the external epithelial 

 cells and not as is often thought from the cells of the 

 parenchyma. Careful preparations through the growing 

 region of a Taenia show that the flame-cells are not formed 

 by a parenchyma-cell fusing with the wall of one of the ex- 

 cretory canals, and so acquiring an outlet, but that they 

 grow from these canals, pushing their way into the paren- 

 chyma. Thus Pintner's comparison between the flame- 

 cell and a unicellular gland-cell, and between the excretory 

 canal and the duct of the gland cell receives material sup- 

 port. This view of the external origin of the flame-cells is 

 confirmed by the ectodermal origin of the excretory system 

 in Discocelis tigrina described by Lang. 



The interesting discovery of transverse commissures 

 connecting the lateral nervecords in Tapeworms has just been 

 announced. Mr. Tower,^ to whom we owe the discovery, 

 studied two species oi Moniezia, M. ex/fansaand M.planissima 

 both from the small intestine of sheep. He obtained the best 

 results by using von Rath's preserving fluid, which stains 

 the nervous tissue a greyish blue, and the muscles brownish, 

 the connective tissue remaining lighter in colour than 

 either. 



Each lateral nerve cord swells out into a ganglion (Fig. 

 Il.y) at the posterior end of each proglottis, just behind 

 the level of the transverse excretory canal. The ganglion 

 consists of two kinds of ganglion cells, large and small, 

 and gives off externally several fine nerves, of which one 

 runs forward and is called by Tower the marginal nerve 

 (Fig. II. e). The most important branches which arise 

 from the ganglion are, however, a dorsal and a ventral one 

 which traverse the proglottis and end in the corresponding 



1 Zool. Anz., xix., 1896, p. 323. 

 6 



