592 
DR. NELSON ON THE REPRODUCTION OF THE ASCARIS MYSTAX. 
nearly ceased and the formation of a chorion begun, c. The vitelline gra- 
nules mueh broken up. f. The first layer of the chorion, perfectly trans- 
parent and struetureless. g. The spermatic particles entering at those 
places in whieh the chorion is as yet imperfect, h. The spermatic par- 
ticles, which having entered have begun to swell, giving the vitellus a 
mottled appearance. 
Fig. 63. A fertile ovum, with the chorion entire, c. The vitelline granules much 
broken up round the margin, f. The chorion, which has wholly encircled 
the ovum. h. The swollen spermatic particles. 
PLATE XXIX. Magnified 330 diameters. 
Fig. 64. Ovum become spherical either from the external imbibition of fluid or the 
liquefaction of the contained granules, a. The germinal spot. h. The 
germinal vesicle slightly enlarged, and become visible by the breaking up 
of the vitellus. c. The vitelline granules much broken up, and partially 
dissolved, f. The chorion become tense and spherical, h. The embryonic 
spot seen within the germinal spot, forming the nueleolus of the germinal 
vesicle, h. The swollen and partially dissolved spermatic particles. 
Fig. 65. Ovum beginning to assume the oval form. a. The germinal spot. b. The 
germinal vesicle, c. The vitelline granules broken up into detatched 
masses, h. Two embryonic spots seen within the germinal spot. m. Fluid 
resulting from the solution of the spermatic particles and vitelline granules. 
Fig. 66. Ovum still containing a germinal vesicle, a. The germinal spot. h. The 
germinal vesiele. c. A few vitelline granules surrounding the vesicle. 
f. The three layers of the chorion, n. The transformed or embryonic 
granules. 
Fig. 6/. Ovum in which all traces of the vitellus and germinal vesicle have disap- 
peared. a. The germinal spot set free by the disappearance of its vesicle, 
but still solid, f. The chorion, h. The embryonic spot enclosed within 
the germinal spot. n. The transformed or embryonic granules floating 
free in a clear fluid. 
Fig. 68. Ovum with the first trace of an embryonic vesicle, a. The embryonie 
vesiele formed by the swelling up of the germinal spot. k. The embryonic 
spot. n. The embryonic granules still free. 
Fig. 69. Ovum with the separation of a yolk-membrane, f. The three layers of 
chorion, n. The embryonic granules, o. The yolk-membrane separating 
from the interior of the chorion, and contracting irregularly on the 
embryonic granules. 
Fig. 70. A perfect ovum, in which state it is expelled from the vagina of the female. 
