298 ANIMAL PARASITES. 



cells lining the oviduct, which represent the epithelia, and have 

 nothing to do with seminal corpuscles. Consequently we must 

 not regard the seminal corpuscles as epithelium, as the same 

 changes are never exhibited by such epithelial cells, as are 

 described in the seminal corpuscles, and vice versa. This asser- 

 tion of Bisschoff only had a passing success, and must be 

 regarded as controverted. 



3. Meissner, who describes the seminal corpuscles as pene- 

 trating into the vitellus through a particular opening {micropyle), 

 states, that the fecundation takes place, at least in the Ascarides, 

 in the albuminigene, in which the eggs arrive naked, without 

 chorion, and with an open micropyle. The production of the 

 micropyle would be easily explicable according to the above 

 statements of Meissner. The egg remains open at the point 

 where it was attached to the mother-cell by means of the stalk, 

 where it exhibits a canal-like process, and allows the vitellus to 

 escape on the application of a gentle pressure. The eggs which 

 stood in the form of a circular disc around a germ-cell in the 

 germ-stock behave in the same way. There are also eggs 

 produced singly from the germstock, which are connected with 

 the walls of this canal. The orifice of the stem, after separation, 

 takes the place of the micropyle. Through this the seminal cor- 

 puscles enter the egg. Its lumen is usually turned towards the 

 tuba from which the seminal corpuscles advance. The seminal 

 corpuscles may also reach the micropyle by the pressure of the 

 egg-tubes, which exhibit peristaltic movements, and by the 

 agency of friction between the eggs. 



4. Thompson found in all females of Ascaris mystax, and at 

 all times when males were simultaneously present in the intestine 

 of the cat, seminal corpuscles mixed with eggs in the female 

 efferent organs, and in the upper parts of the oviduct (albumini- 

 gene), appearances similar to those which Nelson describes and 

 figures as the penetration of the seminal corpuscles. On the 

 passage of the eggs from the so-called germ-stock into the true 

 oviduct they changed their consistence, became soft and ex- 

 tremely yielding to pressure, and in passing through the narrow 

 parts of the oviduct they altered in their form. At the same 

 time the eggs acquired the uneven appearance described by 

 Nelson, and single or numerous seminal corpuscles adhered to 

 their surface ; such seminal corpuscles were far more rare on the 

 smooth parts of the eggs. They sat upon the vitellus, sometimes 



