

I7 6 ' ' BOTANICAL GAZETTE [ius.cs 



in the late prophase (figs, j, 7) and anaphase (figs. 6, 12a, 12b) in 

 the polar view of the equatorial plate. In metaphase, the chromo- 

 somes at the equator split and separate, and in anaphase two sets 

 of daughter chromosomes proceed toward the poles (figs. 4, 10). 

 The sets of daughter chromosomes when they reach the poles no longer 

 remain in one plane, but become aggregated into more or less irregu- 

 lar spherical masses which then become vacuolate. Probably through 

 the interaction of the nuclear sap, derived perhaps from the variola- 

 tion, and of the surrounding cytoplasm, a new membrane is organized, 

 thus completing the process of typical mitosis. 



The centrosomes that were always observed staining black at 

 the poles lose gradually their sharp identity, until they can no longer 

 be differentiated by stains. 



MITOSES IN ANTHERIDIA 



In Fucus antheridia develop from wall cells of the conceptacle. 

 A wall cell of the conceptacle puts forth a papilla which is cut off 

 by a transverse wall (fig. 13). The papilla"'qrows for a time and 

 divides, forming the antheridium and its stalk (fig. 14)- A stalk 

 cell may produce again either several antheridia directly or a papilla 



antheridium 



r 



formation again and again, so that there are produced 



numerous 



The young antheridium enlarges after its formation until it 

 length becomes 2-4 times greater than its breadth, the growth of the 

 cell being accompanied by that of its nucleus. The cytoplasm 

 contains deeply staining granules and is very dense, especially in the 

 neighborhood of the nucleus. The nucleus in the resting condition 

 contains a comparatively large amount of chromatin substance 

 arranged in a network evenly distributed throughout the nuclear 

 cavity. At this time neither kinoplasmic accumulations nor cen- 

 trosomes are differentiated. The nuclear network, composed ° 



(fig- 15) • 



i transformatio 



transformed 





iticulum 

 the 



to a thread accompanies the first manifestation of polarity m 

 nucleus; for it does not occur simultaneously throughout the ca 



