No. 3-] 



SPERM A TO PH ORES 



385 



formed in the median unpaired tube lying beneath the nerve- 

 cord. 



The foregoing facts enable us to form some idea of what 

 probably goes on each time a spermatophore is produced. My 

 conjecture is as follows : As soon as the sperm-case is ready for 

 the reception of its burden, the corpuscular secretion and the 

 spermatic fluid contained in the convoluted tube (w, g^ and d) 

 are driven forward into it. The contents of this whole tube 

 between the horn {s) and the vesicle (ys) is probably required 



Fig. 3. — Section of the terminal horn of the efferent duct, just below the point 

 of union with the ejaculatory coil. The epithelial layer is still more strongly devel- 

 oped. The cells are fixed in the act of secreting a spermatophore; the secretion 

 still shows its origin from numerous single cells. 



for a single charge. The spermatic fluid would sweep the cor- 

 puscular mass before it, and leave it in the basal portion of the 

 sperm-case. Whether any portion of the contents of the vesicida 

 seminalis is needed in addition to that of the ductus ejaculatorius 

 to complete a single charge, is a matter of doubt. I am inclined 

 to think that the charge is measured off each time in the ejacu- 

 latory ducts, and that the contents of the vesiculcB seminales is 

 brought forward only to replace what has been ejected. 



