CLOACA AND SPERMATHECA OF GYRINOPHILUS. 



26l 



expands into two short but thick lateral branches. These 

 branches curve both latero-ventrad and caudad (Figs. 5 and 12). 

 Into them and into the distal end of the common tube open 

 small flask-shaped tubules, with long slender necks and bulbous, 

 blind ends; these are bilaterally arranged in two groups, varying 

 from fifteen to twenty-five in each group in different animals. 

 Rarely a tubule is double: i.e., one slender neck terminates in 

 two bulbs. The tubules point caudad, dorso-caudad, laterad 

 and ventrad, but not cephalad and not directly dorsad. Sperma- 

 tozoa, when abundant, are found in the common tube, its 

 branches, and in both neck and bulb of the tubules (Fig. 12). 

 In the bulbs they are arranged in a whorl (Fig. 13), lying side 

 by side, heads all pointing in the same direction. A similar 

 cluster is sometimes found streaming into the neck of a tubule, 

 but in other necks and in the common tube, there are only a few 

 stray sperms. When sperms are scanty, they are tangled and 

 disordered, as though they had been brushed off when the larger 

 clump was expelled by muscular contraction, and are found in 

 the lateral branches of the common tube, and in some tubules, 

 but are absent from others. 



Surrounding the organ as a whole, as well as each tubule and 

 the common tube, are numerous plain muscle fibers. Pigment 

 cells, containing coarse black or brown granules, are found to be 

 most abundant around the expanded end of each tubule, moder- 

 ately abundant in the dorsal elevation, and scanty beneath the 

 epithelium of the rest of the cloaca, among the muscle fibers 

 of its wall, and about the ureters. 



The epithelium of the spermatheca is stratified in the common 

 tube and its branches, the surface layer of columnar cells be- 

 coming progressively taller toward the upper end of the tube. 

 It becomes a simple, low columnar in the necks of the tubules, 

 and a simple, tall columnar in their expanded ends. In this 

 location the cytoplasm takes a deeper eosin stain than in any 

 other part of the organ, and is finely granular. 



The size of the spermatheca in animals of 16.5 cm. length is 

 approximately 1.05 to 1.20 mm. in each of its dimensions (trans- 

 verse, cephalo-caudal and dorso-ventral, including the common 

 tube). If larger, it is the transverse diameter which is most 



