286 Cardiff : Synapsis and reduction 



Salomonia biflora (Walt.) Britton 



This form affords especially good material for study. The 

 acropetal development of the flowers in the inflorescence, which at 

 the time of reduction is still quite short, enables one to get in each 

 section a series of stages in the development of sporogenous 



tissue. 



In the very early mother-cell the cytoplasm is in a very fine 

 alveolar or granular condition. There are generally present several 

 nucleoli (figure 36). As the cells get older the threads of the 

 reticulum become coarser and take the stain more strongly ; the 

 cytoplasm losing its alveolar character, later becoming fibrillar and 

 containing many conspicuous deeply staining granules (figure 44). 



The stages are passed through quite rapidly, so that material 

 must be collected at frequent intervals in order to be sure of stages, 

 though the cell seems to pass some time in the stage shown in 

 figure 36. In order to meet this condition, in part, many rhizomes 

 of the plant were taken up early in the spring, brought into a green- 

 house and forced. Collections were made from these at all times 

 of day. Material was also fixed in the field at different times. 



As soon as the mother-cell commences to increase in size the 

 chromatin commences to increase and is organized into threads 

 which, as in Acer, leave the nuclear wall and traverse its cavity. 

 The chromomeres increase in size and seem to spread along the 

 linin thread, which either becomes chromatin or is obscured by it 

 until at the contraction stage of synapsis no trace of linin, as such, 

 is in evidence. With the change in the chromatin from a reticulum 

 to a spireme there begins an arrangement of threads parallel to 

 each other which show as far back as the stages shown in figures 

 37 and 38. This parallelism becomes more marked — even more 

 than in Acer 



44). Here, too, the collection of the threads near the nucleolus 

 or the movement of the two to the same side of the nucleus is 

 apparent. 



As the chromomeres approach each other they seem to become 

 much more active, increasing in size and staining more strong y> 

 than when at a greater distance even in the same nucleus, inis 

 is shown in figure 43*7, where the threads are still widely sepa- 

 rated. A careful examination of the material from which figures 



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