FECUNDATION OF THE NEMATOIDA. 305 



stance, by the seminal corpuscles sometimes attaching them- 

 selves with this end to the inner surface of the albuminigene), 

 and therefore to the vitelline membrane and its micropyle, whilst 

 the opposite smooth end of the seminal corpuscle can never effect 

 any such adhesion. Such an egg, with its seminal corpuscle 

 adhering to the micropyle, looks like a pear with a stalk, 

 the latter being represented by the seminal corpuscle. At 

 first, indeed, before the seminal corpuscle has fixed itself, only 

 contact may take place. As soon as the flocculent end of the 

 seminal corpuscle is firmly fixed in the micropyle, whilst the 

 upper extremity still projects freety, movements may be detected 

 in the egg which are communicated to it by the seminal cor- 

 puscle, whilst the further penetration of the seminal corpuscle 

 into the interior of the egg, consists in a flowing in. Auxiliary 

 momenta in the advance of the seminal corpuscles towards the 

 micropyle, are to be found in the direction of the micropyle 

 within the albuminigene towards the tuba; the peristaltic motion 

 of the tube, which may be seen very well, as I have already 

 stated, in all parts of the egg-tube in Oxyuris vermicularis, and the 

 action of the external muscular layer upon the albuminigene, and 

 the movement thereby produced, so that the eggs gradually 

 become rounded in the albuminigene. The entrance of the 

 seminal corpuscle into the egg may take place pretty rapidly, for 

 in the lower part of the albuminigene we usually find eggs with 

 seminal corpuscles in the periphery of the yelk, between it and 

 the vitelline membrane. The number of seminal corpuscles 

 which enter varies; as many as ten of them have been observed in 

 one egg. As soon as the seminal corpuscles have performed their 

 function, they enter upon a retrograde development, namely, a 

 gradual conversion into fat. This is the case, however, not only 

 with those which are lucky enough to get into the eggs, but 

 also with the great number of unemployed ones, which are thus 

 again excluded from the female organs, and lastly, also with 

 those which have missed their object by being prematurely deve- 

 loped, and remain in the testis or vesicula seiimialis. The 

 fatty metamorphosis shows itself in this manner : the outline of 

 the bell-shaped portion of the seminal corpuscle begins to grow 

 sharper and darker, acquires a peculiar fatty lustre, has greater 

 refractive power, and a rounder form, whilst the lower extremity 

 gradually contracts to form a simple, clavate, thickened end, 

 having its nucleolar corpuscle in the middle, or the seminal 



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