Nuclear Phenomena in the Smuts. 
487 
of the other remains quiescent, as seen in Fig. 21, thus indi¬ 
cating clearly its independent individuality. In the case 
figured the sterile spore is somewhat smaller than the other and* 
its nucleus is also smaller. In the germinating spore the nucleus 
divides to furnish nuclei for the cells cut off from the germ 
tube. One nucleus always remains in the spore itself. Brefeld 
reports 1 that he finds no difference between the fused and un¬ 
fused conidia in their ability to live through a starvation per¬ 
iod. In my own cultures, however, a marked difference was al¬ 
ways noticeable in the per cent, of paired and unpaired cells 
which survived after a period of two or three days of starva¬ 
tion. 
There is no evidence that a thicker wall is formed about the 
conidia after fusing in pairs. So far as they show greater 
ability to live through unfavorable conditions it is apparently 
due to some change in the protoplasm. Exceptionally germina¬ 
tion occurs from the fusion tube. In this case nuclei are seen 
still present in the two spores, and it is uncertain which of 
them divided to form the nucleus for the conidium. The whole 
fusion process may be summarized as follows: 
1. In cultures several days old when starvation threatens, 
the conidia put out tubes which fuse end to end, thus establish¬ 
ing protoplasmic continuity between the two cells. 
2. No nuclear fusions or visible interchange of nuclear sub¬ 
stance accompanies this cell fusion. 
3. The cells enlarge rapidly in size and show increased pro¬ 
toplasmic content, indicating a stimulation of anabolic pro¬ 
cesses as a result of the fusion. 
4. Fusion also regularly occurs between the basal cells of the 
promycelia under the same conditions. 
5. Conidia which have not fused in pairs and the end cells of 
promycelia which have not fused with adjacent conidia, are 
somewhat less resistant to prolonged starvation than are the 
fused pairs. 
6. The germination of the fused pairs is directly by budding, 
or a short one to three celled germ tube is produced which buds 
out in conidia. 
1 Loc. cit., pp. 48-49. 
