CENTRAL BODY IN PHYLLACTINIA. 53 



THEORETICAL DISCUSSION. 

 THE CENTRAL BODY IN PHYLLACTINIA. 



We find in the above-described series of nuclear fusions and 

 divisions not alone the persistency of a central body as such, but a center 

 that remains throughout in intimate and organized connection with the 

 chromatin content of the nucleus. The center is not a naked granule 

 or centrosphere which can be distinguished only with difficulty from 

 other stainable granules in the neighborhood of the nucleus. It con- 

 stitutes throughout a point of attachment for the elements of the nucleus, 

 and in all the various modifications which it and they undergo in the 

 processes of division and fusion this relation is maintained in the most 

 definite fashion. The central body by its position determines in an 

 important sense a definite polar organization on the part of the chro- 

 matin, and thus of the nucleus as a whole. At no stage in its develop- 

 ment is the nucleus of Phyllactinia an isotropic or radially organized 

 body. In every stage the chromatin is definitely attached to either one 

 or two central bodies on the periphery of the nucleus. The nucleus is 

 hence strictly unipolar throughout its so-called resting stages, becoming 

 bipolar by division of the center for the formation of the two daughter 

 nuclei. We can thus distinguish throughout its history both polar and 

 antipolar regions in the nucleus. The position of the central body on 

 the nuclear membrane is characteristic of the fungi, and the greater 

 readiness with which a permanent connection between the nuclear ele- 

 ments and the center can be demonstrated in them is no doubt associated 

 with this fact. 



Further, it is plain that the chromatin elements are throughout defi- 

 nite in number and each one is attached independently to the center. 

 In the so-called spirem stage each chromatin element consists of a 

 relatively thick thread or strand, which is attached at one of its ends to 

 the center, from which it extends back to the antipolar region of the 

 nucleus, where it ends freely, or may be loosely joined to the other 

 strands, or lie in contact with the nucleole. 



In the reconstitution of the daughter nuclei, from the diaster stage 

 on, the chromosomes elongate and pass back into their more diffuse 

 condition without losing their connection with the center; and even 

 when the daughter nucleus passes into the complete resting condition 

 and the chromatin strands apparently anastomose by fibrillar outgrowths 



