SPECIAL NUCLEAR PHENOMENA. 35 



young ascus. I have elsewhere described (37) such mycelial nuclei 

 as finely granular, and the description applies to the vegetative nuclei 

 of Phyllactinia. It is clear that these granules are the chromatin 

 elements in a finely divided and distributed condition, such as has been 

 commonly associated with the resting condition of the nucleus. In 

 all the vegetative resting nuclei of Phyllactinia, however, the central 

 body is in intimate connection by delicate fibrill?e with this granular 

 content of the nucleus, and, since the antipolar region of the larger 

 nuclei of the young asci shows a similar granular appearance with the 

 linin fibrillas connecting the granules into a reticulum, it is probable that 

 this represents the structure of the resting nuclei generally in this 

 mildew. In the resting nucleus the chromatin threads are so loosely 

 distributed and are connected so frequently by linin fibers as not to be 

 clearly distinguishable, the appearance being that of a reticulum ; but 

 the attachment of the chromatin threads to the central body is contin- 

 uous and becomes conspicuous in the process of aggregation by which 

 the apparently scattered granules of the nuclear reticulum of the resting 

 stage are transformed into the spirem thread. 



Tracing the course of any particular chromatin thread, then, at 

 this stage, we may say that it is attached at one end on the central body, 

 passes back through the nucleus in a path which may be rigidly straight 

 or more or less wavy or bent, and either ends freely or seems to fade out 

 in the apparently less differentiated granular reticulum of the antipolar 

 region. The whole series of threads forms a broader or narrower cone 

 or pencil of coarse rays extending from the central body into the nucleus 

 and filling more or less completely the nuclear cavity. The outline of 

 the more dense portions of the nucleus is determined by the outline of 

 the chromatin system. The nuclear membrane may lie on the surface 

 of this chromatin mass or it may be separated from it by a zone of clear 

 non-stainable nuclear sap (fig. 31). Frequently this zone of nuclear 

 sap extends around the whole surface of the chromatin system, except 

 where the threads are fastened to the central body. The relations of 

 the threads to the centers is much emphasized in such cases, in that the 

 center is the only point in which the chromatin is in contact with the 

 nuclear membrane, and thus with the cytoplasm of the cell. Such 

 figures indicate, as I have suggested in an earlier paper (38), that the 

 central body represents a special region of connection between the 

 interior of the nucleus and the cytoplasm. 



The connection of the nuclear threads with the central body implies, 

 of course, that the nuclear membrane is not continuous at this point, or 

 at least that it permits in some way the connection of the threads with 



