SECRETING STRUCTURES. 413 



Henle, who referred them to the same class of structures as 

 the closed vesicular extremities of the ducts of compound 

 glands. Dr. Allen Thomson has observed, that the primitive 

 condition of the gastric and intestinal gland is a closed vesicle.* 

 Wasmann described the structure of the gastric glands in the 

 pig ; and his description will be fully explained by the 

 following observations and views.-)- Hallman has given a 

 detailed account of the testicle of the ray,;]; which closely re- 

 sembles that of the Sgualus cornubicus, as described in another 

 part of this chapter. None of the recent observations on the 

 development of the spermatozoa have proved that the 

 vesicles, in which they are formed, are the epithelium -cells 

 of the ducts of the testicle. I am indebted to Dr. Allen 

 Thomson for directing my attention to a notice in Valentin's 

 Repertorium, 1841, of a Dissertation by Erdl, in which he 

 describes, in the kidney of that mollusc, cells, the nuclei of 

 which pass out by the duct of the gland. It does not appear, 

 however, that Erdl had discovered the uric acid within the 

 celL|| 



If the membrane which lines the secreting portion of the 

 internal surface of the ink-bag of Loligo sagittata (Lam ark) be 

 carefully freed from adhering secretion by washing, it will be 

 found to consist almost entirely of nucleated cells, of a dark- 

 brown or black colour. These cells are spherical or ovoidal. 

 . Their nuclei consist of cells, grouped together in a mass. Be- 

 tween these composite nuclei, and the walls of their containing 

 cells, is a fluid of a dark-brown colour. This fluid resembles, 

 in every respect, the secretion of the ink-bag itself. It 



* Proceedings of the British Association, 1840. 



f De Digestions Nonnulla, Diss. manq. Berol. 1839. 



J Miiller's Archiv, 1840. 



De Helicis Algirce vasis sanguiferis, 1840. 



|| Mr. Bowman lias shown that the fat in the fatty liver is contained in the 

 secreting cells. Observations on the Minute Structure of the Fatty Degenera- 

 tion of the Liver, January 1842. 



