272 



DR. J. B. GATENBY ON THE GERM-CELLS AND 



13. Spermatogenesis in Grantia compressa. 



About twenty-five pieces o£ sponge were sectioned by me, and of these 

 only one contained any obvious stages of spermatogenesis. The sperm- 

 elements of Grantia consist of small groups of cells lying in the interstitia 

 between the gastral chambers. Each group lies enclosed in a special 



Text-fig. 1. 



Camera-lucida drawing of part of sponge showing oocytes (OTE) and nests of spermatids 

 (SPT) with tails. Compare with PI. 19. figs. 5 and 5 A. The entire substance of 

 this sponge contained patches of spermatids and isolated growing oocytes ; it was a 

 slightly protogynous hermaphrodite, as some of the oocytes were being fertilized. 



capsule of mesogleal cells, the whole arrangement being unlike anything 

 described by previous authors. 



It is a moot point as to whether each group of sperm-cells should be 

 called a testis ; I think that the cells are too much scattered to form a 

 distinct gonad (text-fig. 1). 



