6 ART. 5. N. YATSU : 



membrane the cells, however, in Lingula appeared to present 



different stages of development, varying much in size and form. 

 Some were oval, others perfectly elliptical, the larger ones were 

 pointed at both ends, and exhibited a double line in the centre, 

 placed longitudinally ; while the largest measuring y-Jôth of an 

 inch [=141 /•*] in length, were fusiform, with the extremities 

 more or less sharply pointed. These corpuscles were filled with 

 numerous delicate hair-like bodies, resembling spermatozoa. From 

 these facts it can scarcely be doubted that the dendritic organ 

 is the testis, and that the fusiform cells are fully developed 

 spermatophora, containing spermatozoa " (p. 819). As far as the 

 microscopical structure of the dendritic organ is concerned, his 

 observations are correct in all essentials, but from the vague 

 premise that the corpuscles contain " hair-like bodies resembling 

 spermatozoa," it was certainly a dangerous conclusion that the 

 " dendritic organ is the testis." It is strange that Hancock's 

 erroneous conclusion passed over to Beyer's view, as will soon 

 be seen. Hancock studied, on the other hand, the ejrithelial 

 ridge and rightly saw the difference between it and the sexual 

 organ found there in other Brachiopods, recognizing the difference 

 in position dependent on the fact that the sexual organ hangs 

 from the inner side of the palliai sinus while the epithelial ridge 

 rises from the outer side (nearer the shell). But unfortunately 

 as he did not study the ridge microscopically he was not able to 

 ascertain that the ridge was the equivalent of the dendritic organ. 

 In the year following the publication of Hancock's memoir 

 there appeared the work of Gratiolet ('6o) on the anatomy of 

 Lingula. In this he expressed the curious view that the spindle 

 bodies were young Lingula. These, he thought, were produced 

 in the body cavity as the result of self-fertilization : he even 



