Ihe Seminal Fluid of Animals. 335 



ed on both sides. The vesicles form within them a round 

 mass, which is often smaller than the space enclosed by the 

 external membrane. Under such circumstances, the discs ap- 

 pear as if surrounded by a transparent ring, which encom- 

 passes a circular space covered with minute globules lying 

 close together. The sacculi of the testicle are also filled with 

 a whitish secretion, more fluid in general than the former, 

 and in which the peduncles or filaments, before described, are 

 seen swimming ; it also contains a much larger quantity of 

 discs. The discs are partly attached to the filaments, and part- 

 ly separated from them. On examining more closely the latter 

 fluid, and the sacculi in which it is contained, the following cir- 

 cumstances are observed : The filaments at their origin lie pa- 

 rallel and close together, and form a species of fibrous mem- 

 brane, which covers the internal surface of the sacculi before 

 mentioned. The ends of the filaments project into the fluid, 

 and form an annulus which encloses a disk. The fibres gradu- 

 ally separate from the surrounding parts, and the discs from 

 them. The ends of those which have lost their discs bend back- 

 wards, and twist themselves in a spiral form round their own 

 stems. These, as well as the filaments, escape with the secre- 

 tion of the testicle into the excretory duct. But as the number 

 of discs found in the latter is much smaller than in the testicle, 

 and yet there is no accumulation of discs observed in the tes- 

 ticle, we are obliged to conclude that they discharge their con- 

 tents in their passage into the excretory duct, and that their 

 external covering is then dissolved. 



" These observations were made chiefly on the Limax ater 

 and Helix nemoralis. If the seminal fluid of these animals be 

 examined at different periods of the year, the proportion of the 

 discs to the vesicles and peduncles is found to differ very much 

 on many occasions. Sometimes one perceives only a few quite 

 transparent discs ; but, on the other hand, a great many vesi- 

 cles and peduncles separated from their discs : at other times, 

 only a few vesicles are observable, but we see a great many 

 discs filled with a dark matter, partly resting on their pedun- 

 cles, partly detached from them. Occasionally, one can see 

 nothing but vesicles and peduncles without discs. Thus, in 

 two wood-snails which I opened on the 1 8th of May, the orga- 



