CALYCULARIA RADICULOSA CAMPBELL 57 



THE SPORE DIVISION. 



(Figure 11.) 



One sporogonium showed the spore mother cells in process of division, 

 all stages occurring in the same sporogonium. The preparation was some- 

 what overstained with haematoxylin, but nevertheless showed pretty well the 

 details of division, which exhibited a considerable amount of variation. 



The spore mother cells before the first nuclear division are deeply four- 

 lobed, the lobes being usually arranged tetrahedrally, but occasionally placed 

 in pairs at right angles to each other (Fig. 11, J). The nucleus is large, 

 but in this over-stained material the structure was not usually very clear, 

 the nucleus appearing almost homogenous. A few specimens, however, 

 (Fig. 11, E) showed a more or less granular structure, but the reticulum was 

 not clearly evident nor could the nucleolus be seen. 



A striking feature was noticed in most of the cells, viz. : the extension 

 from the nucleus into each of the four lobes of the cell of a body which was 

 apparently the same as the "quadripolar" spindle described by Farmer for 

 Pallavicinia decipiens^. Often the center of each lobe was occupied by a 

 roundish body which perhaps marked the position of a centrosome, but it 

 cannot be stated positively that centrosomes are present. However, as cen- 

 trosomes occur in Pellia, which in some other respects suggest a relationship 

 with Calycularia, it is possible that centrosomes may have been present in 

 this case also. 



In the later stages of nuclear division some difiFerences were found to 

 occur. Usually the process seems to agree very closely with that described 

 by Farmer for Pallavicinia decipiens. The nuclear membrane disappears 

 and the separate chromosomes, thick oval bodies, can be made out. (Fig. 

 11, F.) There are eight of these in Calycularia radiculosa instead of the 

 four found in Pallavicinia decipiens; but it was found that in Pallavicinia 

 radiculosa there were also eight, as there are in Pellia. 



The eight chromosomes next divide longitudinally (Fig 11, G), and 

 the resulting sixteen chromosomes separate into two groups ( H ) . Usually 

 the chromosomes do not arrange themselves into a new reticulum, but imme- 

 diately undergo a second division, so that there are two groups of 16 chromo- 

 somes (Fig. 11, I), each of which separates into two. secondary groups of 

 eight chromosomes which finally assume the form of resting nuclei. One 



8 Farmer, J. B. Studies in Hepaticae Pallavicinia decipiens Mitten. Ann. of 

 Botany, 8, 35-52, 1894. 



