Royal Society. rS¥ 



'-7. "On the Reproduction of the Ascaris Mystax^ By Henry 

 Nelson, IVLD. Communicated v fey AUeft Thom80fi,'^:MlI>.rF;HiS. 

 Received May 22, 1851. ' ^ - rr.';.: s 



The author commences with a brief anatomical description of the 

 Ascaris Mystax, found in the intestinal canal of the Domestic Cat ; 

 with more especial reference to the organs of generation in the two 

 sexes. Me traces tlie gradual formation of the semen ; originally 

 thrown off as seminal particles by the ctecal extremity of the tubular 

 testicle, the exterior of each solid particle enlarges to constitute a 

 cell, while the interior retains its consistency and forms a nucleus. 

 The cell then acquires a granular protecting envelope, and in this 

 state is introduced into the female. The solution of the protective 

 envelope and the great enlargement of the seminal cell follow, and 

 its nucleus is now seen to present a granular structure. The exter- 

 nal granules of the nucleus coalesce to form a membrane, at first 

 exactly resembling a watch-glass in shape, but by the contraction of 

 its margin ultimately forming a curved ca3cal tube. This is the 

 true spermatic particle or spermatozoon, and is set free by the 

 rupture of the seminal cell. 



The generative apparatus of the female, commencing also in caical 

 extremities, is next treated of, and the author draws particular atten- 

 tion to a transparent, narrow contractile portion, the oviduct, inter- 

 vening between the ovary and uterus, as the part in which the ovule 

 encounters the spermatic particles, and is by tliem fecundated. 

 The caecal end of the ovary likewise throws off a solid particle, 

 which enlarging forms a germinal vesicle and spot. As the ger- 

 minal vesicle travels slowly down the tubular ovary, it acquires a 

 thick granular investment or yolk, secreted by the ovarian walls. 

 The ovules now present a flattened triangular shape, are placed side 

 by side, and form one solid mass. At the commencement of the 

 oviduct however they become detached, separated from each other, 

 and propelled singly along its interior. Here the gelatinous ovule 

 meets the tubular spermatic particles, and is surrounded on all sides 

 by them. They are at first seen to be merely applied against the 

 ovule, but by degrees the margin of the latter presents a rupture, 

 some of the vitelline grannies are displaced, and the spermatic par- 

 ticles become imbedded in the substance of the yolk itself. 



While the penetration of the spermatic particles is going on, a 

 chorion, secreted by the oviduct, surrounds the ovule, forming a 

 spherical envelope, within which the germinal vesicle, the granular 

 yolk, and the imbedded spermatozoa, are enclosed. The spermatic 

 particles after penetration are seen to svvell, become transparent, and 

 ultimately to dissolve. The vitelline granules likewise either disap- 

 pear altogether, or are transformed into others of a different colour ; 

 and, lastly, the germinal vesicle is destroyed. 



By tracing the changes of the ovule in unfecundated females of 

 the same species, the author finds the disappearance of the vitelline 

 granules to be dependent upon, while the formation of the chorion 

 is wholly independent of, the influence exertj^d ^^)y._the spermatic 

 particles on the ovule. ^ ' 



