368 BOTANICAL GAZETTE [November 



division of the sporophyte, why might it not be tnie of all the mitoses 

 in the sporophyte generation ? This would make half of the chromo- 

 somes paternal and half maternal in every sporophyte cell. Thus in 

 the mother cell two spireras would be formed as usual, but here 

 they would pair and fuse more or less completely in synapsis. If 

 there are two phenomena in fertihzation — stimulus to growth and 

 the minghng of ancestral quahties— only the first would be felt in the 

 sporophyte. The mother cell would give the opportunity for the 

 second during the fusing of the pairs of threads- 



The chromosomes of the fusing nuclei are often arranged in 

 groups, and while these may not be definite enough to be positive 

 evidence for distinct chromatin if taken by themselves, they are not 

 only very suggestive but appear as distinct as the position of the 

 nuclei in the spirem stage would lead one to expect (figs. ^ly 54)- 

 In a form in which the paternal and maternal chromosomes differ, 

 proof could be obtained; but even in Cypripedium, in such groups 

 as those shown in jigs, 51-54^ the chromosomes are evidently of 

 separate spirems. This seems very clear when these figures are 

 studied in connection with those showing the spirems {figs. 42^ 43^ 

 44^ 47, 48, 51, 5j). The groups are just about as distinct as would 

 be expected, for the nuclei usually overlap slightly in the spirem 



stage. 



Synapsis. 



Cardiff 



others have recently discussed synapsis and the stages leading up to 

 and following this condition. It seems to be clearly estabhshed that 

 in the forms studied by these authors there is a gradual pairing of the 



first 



The two 



threads are apparently united into a single thread by the time the 

 nucleus comes out of synapsis. During synapsis itself and in early 

 stages of the recovery from this condition some traces of the double 

 nature of the thread are often seen, and the heterotypic chromosome 



from 



These stages were well shown 



{figs. 2-11). Berghs sees in this a device for reducing 



may 



mixmer 



paternal and maternal chromosomes that have remained distinct 

 throughout the sporophyte stage. Cardiff (10) thinks the position 



