492 EMBRYOLOGY OF THE TURTUE. Part III. 
at first; and notwithstanding the most diligent search, my efforts to trace the sper- 
matic particles through the oviduct, as high up as the ovarian eggs, have been 
unsuccessful. Turtles do not copulate in confinement ; and those which I could 
catch in coitu in their native haunts have only exhibited spermatic particles in 
the oviduct. I have, still less, been able to trace the sperm into the egg itself 
Indeed, there is no micropyle in the egg of Turtles; and I must confess that I 
have not yet seen the first fact which could lead me to admit that the spermatic 
particles penetrate into the egg. I am therefore obliged to abstain from expressing 
any decided opinion upon the question of the penetration of the spermatic par- 
ticles into the ege, which has of late attracted so much attention among embry- 
ologists. I can only say, that, notwithstanding the high authority upon which it 
is asserted as a fact that the spermatic particles do pass into the substance of 
the ege through a definite aperture of its envelope, I am still rather inclined to 
doubt it. 
The aperture observed in the outer membrane of the egg, which has been 
called micropyle, has always appeared to me to be the result of the separation 
of the sac in which the egg is developed, and by no means to pass through the 
vitellne sac. Without the most careful examination it is not possible to per- 
ceive how complicated the sac is, in which the egg is inclosed; and I suspect 
that a kind of Graafian follicle, which in many animals drops from the ovary with 
the egg, has frequently been mistaken for a vitelline membrane. I believe, fur- 
ther, that the scar resulting from the separation of that follicle forms the open- 
ing called micropyle, and that this opening does not traverse the vitellme mem- 
brane. In Turtles the perforated appearance of the yolk sac arises from the 
presence of the Purkinjean vesicle near the surface of the yolk, and not from the 
existence of a real hole. (Comp. p. 456, 459, and 460.) After what has been 
said above of the lateral origin of the Purkinjean vesicle, it is superfluous to 
insist upon the incorrectness of the view of those who would ascribe its super- 
ficial position to the imfluence of fecundation. It is formed in that position, and 
preserves it as long as it exists. 
