414 BOTANICAL GAZETTE [November 



shows any visible signs of activity, affects the cytoplasm to such a 

 degree that the four lobes are organized in advance of the reduction 

 division of the nucleus ; or the cytoplasm, in addition to the nucleus, 

 is an important factor in the reduction division. 



The quadripolar spindle may be distinctly seen at the beginning 

 of the reduction division (fig. 51); but the later stages (figs. 52 and 

 53) verify Moore's interpretation (27) rather than the interpre- 

 tation of Farmer (10). The chromosomes are very short and 

 thick (fig. 48). 



The four young spores gradually separate (fig. 51). At this 

 stage of the sporophyte the greatly elongated nuclei of the elaters, 

 with their strong bands of chromatin and prominent nucleoli, are 

 very striking. The mature spore (fig. 55) measures about 18 . 3 fx in 

 diameter. The echinations are short but very sharp, and a surface 

 view (fig. 53) shows them distinctly reticulate. Spores with two 

 nuclei (fig. 54) are not very common, but enough were found to 

 lead one to think that there is a feeble tendency toward intra- 

 sporal germination. The mature elaters (fig. 55) have two very 



prominent spirals. 



Summary 



1. The thallus of Symphyogyna aspera has a central strand 

 of greatly elongated cells which taper at both ends. The walls 

 of these cells have narrow pores which are spirally arranged. 



2. Like the other species of the genus, S. aspera is dioicous. 

 The plants bearing antheridia are more slender and less freely 

 branched than the plants bearing archegonia. 



3. The antheridia are scattered over the thickened part of the 

 thallus on the dorsal side. Each antheridium is surrounded by a 

 scale. 



4. The archegonia are in groups on the dorsal side of the 

 thallus. Each group is on a padlike extension of the thallus and is 

 surrounded by an involucre. 



5. More than one embryo may be formed in a group, but so far 

 only one has been found to reach maturity. 



6. As the embryo elongates, the calyptra and pad also elongate 

 and the old archegonia are left in the tip of the calyptra. 



