CLOACA AND SPF.RMATHECA OF GYRINOPHILUS. 2JI 



stage. Comparison of these spermathecal tubules with gland 

 tub.ules shows that both originate in the same manner. 



As the tubules grow into overlying tissue, the whole cellular 

 mass likewise sinks somewhat, and a portion of the cloacal 

 lumen is drawn into the cellular mass to form the common tube 

 of the spermatheca. At this stage it is not yet a tube, but rather 

 a shallow depression, pyramidal in cross-section in its caudal 

 part, and communicates widely with the cloaca. In this way 

 the phylogenetic history of the common tube is repeated. One 

 is reminded that in Amblystoma, the first species in the phylo- 

 genetic series to have its tubules aggregated, the common 

 chamber is a depression in the dorsal wall, and apparently 

 merely a modified portion of the cloaca. 



Even at this early stage, however, the common tube gives 

 evidence of enlarging by degeneration of epithelial cells, a 

 feature which is more marked in the following stages. From 

 the first, the caudal part of the common tube indicates its 

 subsequent branching. The caudal portion is next lifted away 

 from the cloaca in a dorsad direction, and becomes the distal, 

 branched portion of the common tube, communicating with the 

 cloaca by means of the old cephalic portion, now drawn out 

 into a long tube. 



Koehring ('25) in describing the development of the sperma- 

 theca in Eurycea, says: "In a 58 mm. animal . . . there are 

 four distinct tubules. . . . These are made up of a very small 

 group of cells closely grouped and darkly stained with barely 

 perceptible lumina and short ducts. The ducts very nearly 

 reach the thick walls of an invagination of the cloacal wall 

 which is the anlage of the central tubule." She does not spe- 

 cifically state in her paper that she regards the spermathecal 

 tubules as epithelial downgrowths, derived from the cloacal 

 epithelium lining the invagination or "central tubule" (common 

 tube); and, since she says that the ducts "very nearly reach" 

 the walls of the invagination, one might surmise that the tubules 

 are formed in the overlying tissue and secondarily unite with 

 the epithelium lining the invagination. If, however, it is the 

 lumen of the duct which very nearly reaches the lumen of the 

 invagination, this would coincide with the findings in Gyrino- 



