558 
DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
Appendix. 
Statements and Conjectures of Physiologists on the Nature, Office, and Destination of 
the Purkinjean or Germinal Vesicle (see par. 323, &c.). 
411. The discoverer of this vesicle was Purkinje ~f~, whose name physiologists have 
justly associated with it. The discovery was made in the ovarian ovum of the Bird. 
Never finding it in ova which had entered the oviduct, Purkinje supposed the vesicle 
to burst, and this from pressure of the oviduct. He supposed it to originate the col- 
liquamentum. Subsequently he expressed the following opinion : “ During the 
generative act and the impregnation following, it bursts and pours its fluid into the 
germinal layer. This process in Amphibia and Birds has been with certainty ob- 
served. * ## How the fluid operates, and whether and in what manner it corresponds to 
the male semen, is a subject for future inquiry, seeing that the effects of the latter 
(the semen) are still entirely unknown;};”. 
412. The discovery of this vesicle was extended to the ova of Mollusca, Annelida, 
Crustacea, and Insects, as well as of some oviparous Vertebrata, by Von Baer§. This 
naturalist supposes “ that the vesicle of Purkinje is the important part of the ovum, 
performing in the female the function corresponding to that performed by the semen 
of the male||.” He conjectures “ that in proportion as the ovum approaches 
maturity, the vesicle is driven forward and finally destroyed between the vitellus and 
its membrane, before fecundation ^[.” He states that the germinal vesicle “ disappears 
towards the epoch of the maturity of the ovum, entirely leaves the vitellus (as I have,” 
says he, “particularly observed in Frogs) and no doubt then bursts, since no traces 
of it are subsequently found'f~'j~.” He remarks, “ Mature ova contained in the ovaries 
of insects have no [germinal] vesicle, while it is found in ova which are not mature^.” 
“ Is the vesicle dissolved or destroyed by the effect of fecundation ? I do not believe 
that this can be the case, for in Frogs the ova which have descended into the oviduct 
are deprived of the vesicle long before fecundation §§.” Respecting the ova of certain 
Fishes the same observer remarks, “I have hitherto found the germinal vesicle in all 
ova which were still in their capsules, but never in such as were discharged ||||.” 
“ The germinal vesicle of Serpents and Lizards does not develope the embryo ; it 
disappears entirely as the germinal vesicle of Birds^[^[.” 
413. Rathke. “The last and most important changes, finally, which take place 
within the ovary, are the disappearance of the Purkinjean [or germinal] vesicle and 
f Symbol* ad ovi avium historiam ante incubationem, 1825. 
X Article “ Ei” in the “ Encyclopadisches Worterbuch,” Band X. p. 112, 1834. 
§ Subsequently, Puukinje discovered it in the ova of Entozoa and Arachnida. 
|| Lettre sur la Formation de 1’CEuf, p. 31. Ibid. p. 30. ft Lettre, &c., Commentaire, p. 44. 
XI Lettre sur la Formation de l’CEuf, pp. 29. 30. §§ Ibid. p. 30. 
1111 Untersuchungen iiber die Entwickelungsgesehichte der Fische, S. 44. 
Lettre, &c„ Commentaire, p. 48. 
