193 M. E. Claparede on the Formation of the Egg 



already formed, still present the pyramidal form, and have the 

 apex very long. Such an egg completely reminds one of IMeiss- 

 uer's drawings of eggs with seminal corpuscles seated upon the 

 micropyle. Sometimes the vitellus draws back a little from the 

 membrane at the apex, and then the resemblance to one of 

 Meissner's seminal corpuscles, with its hood on, becomes still 

 greater. Nevertheless, it is certain that this process is the apex 

 of the egg, and not a seminal corpuscle; for this observation 

 was ahvays made upon females the sexual organs of which 

 otherwise contained nothing that could be regarded as a seminal 

 corpuscle. Closer observation shows also that we have to do 

 here with an extrusion of part of the yelk. The apex gradually 

 becomes constricted, so that at last it is only connected with the 

 ovum by a narrow neck. A false chorion is then deposited 

 around the portion separated by constriction, just as around the 

 unfecundated egs:. For this reason we often find, in the females 

 of Ascaris suilla, besides the ordinary eggs, an immense number 

 of corpuscles which are formed exactly like the eggs, but ex- 

 cessively minute. These are not abortive ova, but portions of 

 yelk throw^n off from eggs of normal size. This is a phse- 

 nomenon agreeing with the separation of a small fragment of 

 vitelline matter, which has already been observed in many ani- 

 mals. F. Miiller's so-called vesicle of direction is nothing but 

 an extruded portion of yelk of this description. We will not 

 assert that such eggs as those just described have furnished the 

 foundation for Meissner's figures, but this is not very improbable. 

 What is most in Meissner's favour is his statement, that he 

 has seen undoubted seminal corpuscles in the interior of ova. 

 We have no right to doubt the correctness of such a statement, 

 although the unmistakeable recognition of a seminal corpuscle 

 within the yelk may not always be a very easy matter. If 

 IMeissner has actually met with seminal corpuscles in certainly 

 uninjured ova, this is an incontestable proof that the zoospermia, 

 by some way or other, penetrate into the egg. Only one of 

 Meissner's figures represents an undoubted seminal corpuscle 

 within the egg. In the text, howevei', the author states that he 

 has sometimes met with three or four seminal corpuscles in the 

 same egg of Ascaris mystax, and that he has since convinced 

 himself (especially in Ascaris megalocephala) that several sper- 

 matozoa (sometimes even ten) usually penetrate into the same 

 e^^. Unfortunately, it is not evident whether this assertion 

 rests upon direct observation, or w^hether the author has con- 

 cluded that there is a simultaneous penetration of several seminal 

 corpuscles, from the fact of his finding the supposed products 

 of their metamorphosis in the eggs. If the last alternative be 

 correct, as appears to be probable, the whole theory of fecundation 



