MUSEUM OF COMPARATIVE ZOOLOGY. 557 



arise by this last act of proliferation. In the case of the ova different in- 

 fluences have been in operation. The vigor of the elements has here — i. e. 

 as compared with the male elements — been a more important factor in 

 the preservation of the individual and the ultimate success of the race 

 than the multiplication of numbers. The last act of proliferation has 

 therefore never resulted, in this case, in the production of more than a 

 very few individual elements, and these have practically been still fur- 

 ther reduced by the suppression of the function of the cells called polar 

 globules, in order to afford the remaining cell (ovum) that increased 

 chance of survival which a better equipment is capable of insuring. 



If this view is tenable, the polar globules are rudimentary structures, 

 and, as such, would be likely to present the peculiarities of such parts.* 

 There is, in fact, a considerable variation in the size of the globules in 

 the same species, and a more conspicuous variability in the promptness 

 with which the reconstruction of the lateral zones of fibre thickenings 

 into nuclei is effected. Accepting Strasburger's conclusions as to the 

 equivalency of polar globules and the "canal cells" in plants, the 

 " Bauchkanalzelle " of cryptogams may perhaps afford even a more 

 obvious instance of variability in size. 



The most important recommendation which this view possesses is the 

 explanation it offers of the morphological condition of the polar glob- 

 ules. It would also serve to explain the signification of the peculiar 

 phenomena observed by Whitman to accompany the production of the 

 globules in Clepsine. The formation of an equatorial constriction might 

 then be viewed in the light of an atavistic tendency on the part of the 

 cell to divide in the original manner into two ova of equal size, and the 

 gradual, orderly shifting of the constriction as a rapid recapitulation of 

 changes slowly realized in the history of the race.f 



* " Eudimentary organs are very liable to vary in development and in other re- 

 spects in the individuals of the same species. Moreover, in closely allied species, 

 the degree to which the same organ has been reduced occasionally differs much." — 

 Darwin, Origin of Species, (5th edit., London, 1869,) p. 538. 



t P. S . — The cases of the penetration of a spermatozoon into a polar cell, re- 

 ported by Fol ('79, p. 246), possibly afford further evidence that these cells are 

 aborted ova. 



