.,' 



r 



I907] PACE— FERTILIZATION IN CYPRIPEDIUM 367 



are the chromosomes of the male and female miclei. Chamberlain 

 (15) in Pinus Laricio finds that "the chromatin appears as two dis- 

 tinct masses in the spirem stage. Perhaps segmentation of the two 

 spirems occurs while they are still separate/' Murrill (32), work- 

 ing with Tsuga canadensis, says: "The chromatin of each (sperm 

 and egg) nucleus collects in the form of a thick knotted thread near 

 the center of the separating partition, and the tw^o masses remain 

 distinct until the spirem band begins to segment-" Miss Ferguson 

 (20), using Pinus, finds "two groups distinct at time of segmentation 

 of spirem and can still be made out during early development of 

 chromosomes; but cannot be when they are being oriented on the 

 nuclear plate." Recently Harper and Blackman have shown 

 interesting features in some of the fungi that seem to be related to 

 this independence of chromosomes. Harper (27) has shown in 

 Phyllactinia that "the material of each chromosome is in permanent 

 connection with the central body throughout the stages of nuclear 

 fusion and the resting condition, as well as in mitosis," Blackman 

 (i) says that rusts which have the aecidial stage have two nuclei in 

 all cells from the aecidiospore to the teleutospore. The two nuclei 

 fuse in the teleutospore and from there to the formation of the aecidio- 

 spores the cells are um'nucleate. More recently Gregoire (23), 

 working wdth roots of Alhum, claims that the chromosomes do not 

 unite to form a continuous spirem in the telophase, but always remain 

 distinct bodies. 



In my material, as shown above, it is quite common to fmd both 

 the fertihzed egg nucleus and the triple-fusion nucleus Avith distinct 



(figs. 42 



48, 51 > 53)' 



advanced 



so that the threads were quite broad, before contact of the nuclei 

 (fis- 47)' Spirems as far along as these wdll evidently be cut into 

 chromosomes without fusing at all. If spirems are often formed 

 separately, it would seem probable that when the nuclei fuse in the 

 resting stage two separate spirems may still be present. Anyone 

 who has tried to trace a spirem will at once recognize how difficult 

 it would be to trace two of these long threads in the same nucleus; 

 and as no one expected to find two, only one was seen until two were 

 found distinctly separated. If there may be two spirems in the first 



