324 J. E. BLOMFIELD. 



begin in the " male ovules " for the preparation of next year's 

 crop of spermatozoa. These changes consist in the multipli- 

 cation of the nucleus till large multinucleated masses are pro- 

 duced, comparable to those found in the snail. By the end of the 

 spring these have reached a considerable size, and the next 

 step consists in an arrangement of the nuclei around the peri- 

 phery of the mass, while the centre part is free from them, 

 and undergoes a kind of liquefaction, thus giving rise to a 

 vesicular body. "As this body has grown from the original 

 " male ovule," it has carried the smaller granular cells which 

 surrounded it on its surface towards the lumen of the sac, 

 where they may be seen resting on the protoplasm of the vesicle. 

 Each vesicle is now composed of a mass of uninucleated bodies, 

 which are the spermatoblasts, and the next stage is the trans- 

 formation of the spermatoblasts into spermatozoa. The exact 

 mode in which this is brought about, M. Duval is unable to 

 state ; but reasoning from what he found in the snail, he 

 thinks it probable that the process is the same, and that a 

 " cephalic corpuscle " is produced while the spermatoblastic 

 nucleus is dissolved and the filament is formed from the plasma : 

 but the existence of the " cephalic corpuscles " he is unable 

 to determine. 



The immature spermatozoa are so arranged that the tails 

 point to the interior of the vesicle, while the heads are arranged 

 radially around the concave inner face. 



When the spermatoblasts have nearly changed into mature 

 spermatozoa dehiscence of the vesicle takes place, and the 

 spermatozoa are carried back to the wall of the sac, bringing 

 the granular cells with them, where they become arranged in 

 bundles, and the s?,me condition of things is found as that 

 which formed the starting point. 



The granular cells, which have been carried back, undergo an 

 increase in size, and become " male ovules ;" destined to repro- 

 duce the crop for the next year; but in teased preparations M. 

 Duval finds that often a bundle of spermatozoa is attached to 

 one of these granular cells, an attachment which he regards as 

 quite accidental, though, at one time^ he was tempted to see a 



