348 BOTANICAL GAZETTE [NOVEMBER 
this with certainty,” and in his second paper he shows spindles with 
the same number of chromosomes. KuUsANo (10) reports definitely 
five chromosomes in S. puerariae. 
The probability that the results thus obtained are accurate is very 
greatly increased by the fact that in Synchytrium there is no differ- 
entiation into soma and germ plasm. Every nucleus becomes either 
directly or through its descendants the nucleus of a spore, which, if 
successful in entering its host, becomes the large nucleus of a primary 
cyst. Ifa variation of the chromosome number occurred at any point, 
it would, on the individuality hypothesis, be perpetuated indefinitely, 
affecting all the nuclei of later generations; whereas in the higher 
plants and animals a variation in the somatic nuclei would be lost with 
the death of the individual organism in which it occurred. It is clear, 
therefore, that if a variation in the number of chromosomes should 
occur only once in the repeated direct divisions through which the 
nuclei of the spores have been derived, it would affect all the nuclei of 
the next generation. Thus, though the nuclei of the later stages of 
the parasite are so small that an irregularity in the chromosome 
number might not be detected, yet in the large nuclei of the succeeding 
generation it could not escape observation. Amitosis plays $0 
important a part in the formation of the nuclei that if chromosome 
variations occurred in only one per cent. of the direct divisions, the 
nuclei of the whole parasite would in the course of a few generations 
become so irregular that it would be impossible to recognize the 
original number of chromosomes when it did occur. It may also be 
remarked that an irregular reduction in the number of chromosomes, 
such as might be expected ‘in the amitoses of a non-sexual organism 
like Synchytrium, could lead, when repeated in indefinite series, t© 
only one result—all the nuclei would finally have only one chromo- 
some. 
On the individuality of the chromosomes 
Modern cytology may be almost said to be built around the theory 
of the individuality of the chromosomes, and certainly no other 
hypothesis has borne so much fruit in valuable results as this. 
Without it the complicated process of mitosis would seem to lack 
significance, and the doubling and reducing of the chromosomes in 
