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very top of this immensely long duct. It may be said that the 

 spermatozoa could find the way up themselves. That I admit might 

 be the case if they were fully developed, and consequently moving 

 filaments ; but it would be impossible for them to get up in the un- 

 developed condition in which some of them are found in the pouches. 

 Besides this, if they were injected into the vagina, why did they not 

 impregnate any of the ova on their passage up ? Impregnation is 

 distinctly seen to have taken place from above downwards, not from 

 below upwards, or in any irregular manner. 



The only satisfactory way of accounting for the presence of sper- 

 matozoa in different stages of development in the copulatory pouches, 

 supposing that they were not generated there, would be to find a 

 channel by which they might enter without having to pass through 

 the 40 inches of oviduct. Now I have carefully searched for such a 

 channel and can find no trace of one. Neither can I find any open- 

 ing into the animal near to the spermatheca except the mouth, and 

 I do not think any one will consider that a likely door for them to 

 enter at. 



I admit that my not being able either to detect a tube or an open- 

 ing into the spermatheca does not incontrovertibly prove that no 

 such tube or opening exists. But I think that fact taken in con- 

 nexion with the others, especially that of the spermatic filaments 

 being found in various stages of development in the pouches, is tole- 

 rable evidence in support of the idea that the organ containing the 

 spermatozoa is the one which generated them. And until we hear 

 some more conclusive arguments on the opposite side, we may con- 

 sider ourselves justified in regarding the spermatheca as testicles, 

 and calling the entozoon a true hermaphrodite. 



In conclusion, I have a word to add regarding the habits of the 

 entozoon I have been describing. I found two of them with their 

 heads projecting through the air-sac of the Cobra, and firmly fixed 

 by their prehensile hooklets to a large blood-vessel ; from which I 

 conclude that they feed directly upon the blood of the animal they 

 inhabit. They appear to be blood-suckers in the strictest sense of 

 the word. In order to get to the blood-vessels to which they anchor 

 themselves by their hooks, the worm has to pierce the surrounding 

 tissues, and the hooks are no doubt made retractile into the de- 

 pression in order to enable the animal again to withdraw its head 

 after it has finished its meal. 



I found in the collection of Dr. Sharpey a fine specimen of an 

 entozoon closely resembling the one I have been speaking of 

 (PI. XL VI. fig. 3) ; the only difference being that it is shorter and 

 thicker, has only nineteen strong projecting rings instead of twenty- 

 seven, and that its tail is conical and not cleft ; farther, that the 

 vagina is about a line in front of the anus. Unfortunately no history 

 is attached to this specimen. 



