Phenomena and Develop matt of Fecundation. 295 



tinuous, but by Boveri 

 bo interrupted. This 

 matters little, however, as the ultimate division of the coil is 

 into a definite and regular number. 



When the egg cell lias attained its mature size, a peculiar 

 occurence takes place. The nucleus approaches the wall, forms 

 a spindle and divides, forming at one side of the large ovum a 

 tiny cell, containing half the nuclear matter and a small 

 quantity of protoplasm from the ovum. This is not all, later 

 a second spindle is formed and again the nucleus of the ovum 

 divides throwing off another small cell. These cells thus given 

 off from the ovum are known as polar globules. These little 

 bodies, long passed by as of no importance, have by the mas- 

 terly studies of later authors, foremost among whom are Van 

 Beneden, Boveri and Weismann, been raised to a most impor- 

 tant position and are intimately connected with late theories 

 of fecundation. 



Minot's Theory of Polar Globules.— What we may term 

 Minot's theory assumes that in the cells both sexes are potenti- 

 ally present. To produce sexual elements the cell divides 

 into its parts ; in the case of the egg cell the male polar 

 globules are cast off leaving the female ovum. In partheno- 

 genetic ova he supposes that enough nude matter is retained 

 since only one polar globule appears to be formed. Van Ben- 

 eden is also inclined to regard polar globules as i . 

 male matter. Minot's theory then is that in every cell of 

 every organism having sexual reproduction that there is an 

 equal amount of female and of male matter, an equal number 

 of male and of female chromatin bands ; and that before the 

 egg can be fertilized, it throws off the male matter that it con- 

 tains as polar globules, so that the pronucleus consists merely 

 of the female matter, of half the ordinary number of chroma- 

 tin bands. The spermatozoon which has eliminated all 

 female matter, enters and supplies the required amount of 

 male matter. So that in the fecundated nucleus thus formed 

 we have again the normal number of male and female chro- 

 matin segments from the different parents, and this nucleus 

 by its segmentation forms every cell of the r 

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