KOTES ON HISTOLOGY OF LINGULA ANATINA. 5 



body and a compact body (vide infra.) at the same time (PL I., 

 Fig. 6). 



3. Spindle Bodies. 



The third element to be described is the enigmatical cor- 

 puscles, known as the spindle bodies. These bodies are so 

 characteristic of Lingula, that they have been referred to in 

 every work concerning this Brachiopod. I shall go somewhat 

 in detail into the history and description of these bodies. But 

 before doing so I may state in advance the main conclusion, that 

 they are formed out of blood-corpuscles in two separate and 

 independent places : one of these being the special areas on the 

 dorsal and ventral body walls, and the other along the ridge 

 which passes along the middle line of every branch of the palliai 

 sinus. 



A. Historical. 



C. Vogt ('45) observed the proliferating ridge of the palliai 

 sinus and figures it in his anatomy of Lingula. But he mistook 

 the ridge for a blood vessel, an error, natural perhaps, since 

 he did not study the ridge by means of sections. 



A. Hancock ('59), in his beautiful monograph on the 

 Brachiopods, considers the proliferating zones in the body walls 

 as a part of the reproductive organs and indeed as the testes. 

 He referred to these zones under the name of the " dendritic 



organ" and studied it in detail: " but further experience," 



he says, " has led to the conclusion that they are really a portion 

 of the genital mass and that from the pressure of the valves, on 

 their being closed, they become occasionally adherent to the 



