560 
DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
without reason that it has been regarded as analogous to the semen, — as a sort of 
female semen-i"-.” The same author on another occasion remarks, “That in the ger- 
minal spot alone lies the sole foundation of the future germinal membrane, is scarcely 
probable. It is rather probable that in the transition, the collective contents of the 
germinal membrane undergo an inward metamorphosis, comprehending, and in the 
same manner changing both parts [germinal vesicle and spot]. This indeed is 
shown by the fact, observed by Professor Wagner himself, that at the period of ma- 
turity [of the ovum] the granules [of the spot] become separate from one another, 
and new granulations arise between them. Besides, the granules of the germinal 
membrane are very different from the granulated substance of the delicate germinal 
spot, in which all isolated corpuscles certainly for the most part fail. If the very fine 
and delicate peculiar granular layer on the inner surface of the vitelline membrane, 
pass into the future germinal membrane (which however is much to be doubted, and 
has more against than for it), the contents of the germinal vesicle after the act of 
conception, could only give the substance for the central portion of the germinal 
membrane, out of which indeed the new individual forms, and which therefore has 
the greatest dignity];.” 
417- The germinal spot on the inner surface of the membrane of the germinal 
vesicle was discovered by Rudolph Wagner, who on making known in 1834, the ex- 
istence of this object, pronounced it to be “ the germ.” In a subsequent paper he 
remarks, “ Germinal spot and germinal vesicle disappear indeed as soon as the ova 
have left the ovary and enter the oviduct. This seems to be a constant law in the 
animal kingdom, and I have never observed an exception, but both elements cannot 
in themselves be lost. They appear only to enter into the mass of the germinal disc 
and to form its central part§.” “In mature ova, impregnated or susceptible of im- 
pregnation, the germinal vesicle disappears. How this takes place, whether in con- 
sequence of a sudden bursting, or through rapid dissolution and liquefaction, flat- 
tening down, diminution of its contents, &c., does not admit of being positively de- 
termined. ## *Thus much is certain, that the germinal vesicle has always disappeared 
as soon as the ovum has left the ovary.* # *The contents of the germinal vesicle, — in 
which with increasing maturity more consistent granulations frequently arise (when the 
germinal spot often dissolves away), — are obviously poured into the space occupied 
by the germinal layer, or disc, and from the anatomical situation must be first de- 
posited in its central part.***Such increased granulations, with the disappearance of 
the original germinal spot, present themselves distinctly, for instance, in the scaled 
Amphibia ; and in Birds and Mammals appear to be present as pale clear globules. 
On the immediate changes consequent upon the disappearance of the germinal vesi- 
cle we have no more than mere hypotheses ; for observation has hitherto given no 
f Entwickelungsgeschichte des Menschen mit vergleichender Riicksicht der Entwickelung der Saugethiere 
und Vogel, p. 28, 1835. Edinburgh Medical and Surgical Journal, No. 127. 
J Muller’s Archiv, 1836. Heft II. pp. 168. 169. 
§ Beitriige, &c., p. 40. 
