122 Arlow Burdctte Stout 



substance along the line of the spirem. At this stage it is seen that the 

 spirem remains attached by fibrils to the nuclear membrane at certain 

 points as at a, and b, of figure 20 as if it were viscous and adhered to it. 

 The chromosomes may appear even to be attached together in various 

 directions by fibrils as shown in figure 20. The serial arrangement is, 

 however, readily traced at many points at least for short distances. The 

 connections between the chromosomes in the line of the spirem become 

 more and more conspicuous. The chromosomes evidently become elon- 

 gated until they form a thin continuous chromatic thread, the leptoneme 

 of Winiwarter (1901). This spirem is much tangled, folded on itself or 

 crumpled. The attachments to the nuclear membrane noted above 

 persist for some time producing such appearances as are shown in figure 21. 

 This figure resembles superficially that produced by second synapsis as 

 described by Miss Sargant (1896 and 1897), Allen (1905), and others, 

 except for the thinness of the spirem. There is some indication of a 

 parallel arrangement of the threads in this stage. This stage is the first 

 figured by Juel (1900), but there can be no doubt that it is a presynaptic 

 stage. The attachments of the chromatic thread to the nuclear mem- 

 brane are not permanent. They break away and when the synaptic 

 knot is fully formed the entire chromatin thread is drawn together into 

 a rather compact mass. It may be possible that delicate linin fibres 

 still connect the mass with the nuclear membrane, but I have not been 

 able to bring them out by staining. 



The diameter of the nuclei in the presynaptic stages varies from 

 8,5 ii to ocasionally 10,0 //. There has been a growth slightly in excess 

 of that exhibited by the nuclei in the prophases of previous divisions. 



The synaptic knot usually lies to one side of the nuclear cavity and 

 it may or may not envelop the nucleoles. There is, however, no such 

 orientation of the knot with reference to gravity as has been especially 

 described by Cardiff (1906). 



There can be no question that synapsis as here described and figured 

 is a normal contraction stage and is not as Lawson (1911a) claims simply 

 due to a swelling of the nuclear membrane away from the chromatic 

 reticulum. Lawson considers that there is no decrease in the chromatin 

 area during synapsis in Smilacina. This is certainly not the case in 

 Carex aquatilis. Figure 22 shows an entire nucleus with a typical sy- 

 naptic knot at its greatest contraction. The chromatin mass measures 

 3,75 a in diameter, while the chromatin shown in figure 20 extends 

 through a diameter of 7,0 ;i. 



The events of synapsis are in sharp contrast to those of the pro- 



