1884.] 55 [Hyatt. 



if they agree with Btitschli, that portions of the nucleus are 

 unnecessary and are resorbed or ejected after conjugation. 



Balfour (Ann. and Mag. Nat. Hist.) 1878, subsequently but 

 independently of Minot's publication, rediscovered the same 

 mode of explanation, but his exposition is not so comprehen- 

 sive as Dr. Minot's, especially with regard to the spermatocysts. 



Balfour, Whitman, and Mark all insist that the polar globules 

 are entirely independent of fecundation, and this is evidently 

 true since as a rule the first polar vesicle appears before impreg- 

 nation, and invariably no connection takes place between the 

 spermonucleus and the feminonucleus beforehand. The his- 

 tory of the early stages of the spindle and the archamphiasters 

 shows their agamic origin especially in those types in which, as 

 in Hydra, Asterias and Echinus, they may be developed before 

 impregnation occurs. Btitschli, Fol, and Hertwig, according to 

 Mark, have satisfied themselves that polar globules may be pro- 

 duced in unfertilized eggs (Bui. Mus., Comp. Zool. vol. vi, pt. 12, 

 p. 449), and Ryder quotes similar opinion of C. K. Hoffman 

 derived from the study of fishes. 



Ryder takes the ground that the formation of polar globules in 

 Ostrea is dependent upon impregnation because they are never 

 formed until after the spermatozoon enters the egg. (Embryog. 

 Osseous Fishes, No. 5, Impreg. of j egg, p. 20.) This author, 

 however, clearly states that it is the vitellus which is entered 

 by the spermatozoon, and does not say that the masculonucleus 

 or the feminonucleus comes in contact with the spermonucleus 

 before the globules are formed. Causal connection between the 

 act of impregnation and the formation of the globules is, there- 

 fore, improbable, since there is no such invariable sequence 

 as is found between the formation of the maritonucleus and the 

 subsequent segmentation of the ovum. 



A similar case is given by Dr. H. W. Conn in his life history 

 of Thalassema (Biol. Labr. John Hopkins Univ. vol. in, no. 1, 

 1884, p. 31.) The first polar globule arises in this form always 

 after impregnation, and the description of the rhythmic periods 

 of activity and rest which accompany and follow the forma- 

 tion of the polar globules is very graphic, and render the author's 

 comparison of the mode of formation of these bodies and the 

 primary segmentation of the egg after the maritonucleus is 



