﻿242 BOTANICAL GAZETTE [april 



possible that the large nucleus present in the center of the mature 

 egg was ever so small as the degenerating nuclei whose remains 

 may be found in advanced stages of oogenesis {^fig^ i6), and 

 sometimes even in the fully formed eggs {figs, ij and ^j); but 

 there seems to be no doubt of this. The nucleus destined to 

 preside over the ^^"g is at first indistinguishable in size or struc- 

 ture from many of its neighbors. What should lead to its selec- 

 tion as the ^gg nucleus ? I can see no other explanation than 

 that its position gives it dynamic advantages, enabling it to sur- 

 vive when its neighbors lack the metabolic conditions necessary 

 for nuclei and consequently must degenerate. This conceives 

 the oogonium as too richly stocked with nuclei for the metabolic 

 conditions of oogenesis, and in consequence the field of a struggle 

 of the parts (*'der Kampf der Theile," Roux) . 



What is the relation of the coenocentrum to these events? 

 As we have stated, the coenocentrum is not a permanent organ 

 either in the oogonium or the egg. It appears with the first 

 indications of the ^^g origins and passes away as the eggs grow 

 older. It is obviously a transitory structure peculiar to the most 

 active periods of oogenesis. To the writer, the coenocentrum 

 seems to be the morphological expression of dynamic activities 

 in the oogonium, and especially in the ^^^ origins at the time 

 when these are differentiated. It has the appearance of being 

 the focal point in the center of the ^gg origins of the metabolic 

 conditions peculiar to oogenesis; and this offers a very plausible 

 explanation of the survival of the nucleus which lies nearest the 

 coenocentrum. 



The nucleus most fortunate in its position near the coenocen- 

 trum should be greatly benefited if this is a region of the proto- 

 plasm more favorably nourished than other parts. It is probable 

 that the coenocentrum even draws toward itself nuclei within a 

 certain sphere of attraction. Nuclei maybe found with a pointed 

 end extended toward the coenocentrum {figs, i6, 20). It will 

 be remembered that Stevens (1901) showed with great clear- 

 ness for Albugo Candida and A, Tragopogonis that the nuclei in 

 the immature eggs stretch toward the coenocentra so that their 

 long dimensions are frequently twice the width. The nuclei of 



