Cardiff : Synapsis and reduction 283 



seen 



gators on reduction called the first longitudinal split. Figure 12 

 is a portion of a thread from a stage a little earlier than that shown 

 in figure 13. It shows the chromomeres blended while the linin 

 portion of the thread is not in contact. In looking at a prepara- 

 tion like this it is difficult to think of it as a split, especially if one 

 considers the chromatin as the active element of the nucleus. The 

 slender threads are relatively widely separated in the presynaptic 

 stages and as they approach the knot stage they come closer to- 

 gether until in the knot condition they are so closely blended that 

 only occasionally, figures 14 and 15, can two threads be 

 These are evidently the same stages figured by Allen in Lilium, 

 Berghs in Convallaria, Allium, etc. 



That the synaptic knot is a region of great activity is indicated 

 by the way in which it resists the extraction of stains (safranin 

 and iron-haematoxylin). That this is due not to the mass effect 

 alone is shown by the fact that a small section cut from one side 

 of the knot behaves in the same way. The contraction of the 

 chromatin threads into the synaptic knot invariably occurs at one 

 side of the nuclear cavity and in close contact with the nucleolus, 

 the latter being almost surrounded by the threads at times. Often 

 loops of thread or threads extend outward some distance from the 

 knot, but these loops are always few in number — much less than 

 the number of chromosomes — and show no such regularity in 

 arrangement and number as those figured by Farmer and Moore 

 ('05). Montgomery ('05) reports that he finds the synaptic knot 

 always on the side of the nucleus bordering upon the greater bulk 

 of cytoplasm in the cell. This does not accord with my obser- 

 vations. In fact the knot seems to be as often, if not more often, 

 on the side of the cell where there is the least cytolasm. It was gen- 

 erally found, however, that in any one sporangium or group of spor- 

 angia all the knots occupy the same relative position in the nuclei. 

 I offer as a tentative explanation of this that the chromatin mass is 

 of greater density than the nuclear sap and the position of the 

 nucleolus and knot is due to gravity. From the material with 

 which I worked it was impossible, however, to determine this for a 

 certainty. 



As the threads emerge from the synaptic knot they show no 

 differentiation into linin and chromatin, but instead a continuous 



