CHROMOSOME NUMBERS IN METAZOA La 
general conclusion was that chromosome number should be con- 
sidered as an important factor in taxonomy and that animals 
having widely different numbers should be placed in different 
genera. McClung has also been a strong advocate of the value 
of chromosome numbers in taxonomy. Della Valle’s? list in 
1909 is of little value, as it is a prejudiced one, given entirely 
with the object of showing that chromosome numbers are incon- 
stant and of little importance. Two comprehensive lists of chro- 
mosome numbers in plants have appeared recently, Tischler’s!® 
and Ishikawa’s'" in 1916. The latter is exclusively a list of 
numbers, his general conclusions being reserved for a further 
publication. Tischler’s list is accompanied by able discussions 
and criticisms, his general conclusion being that it is still too 
soon to solve any large phylogenetic problems on the basis of 
chromosome investigations. It may be of interest as a compari- 
son with the work on animals to give some of his statements 
concerning numbers in plants. The Asco- and Basidiomycetes 
have very small numbers, the mosses and Gymnosperms in gen- 
eral small numbers, whereas the Algae, Pteridophytes and Angio- 
sperms have species with both small and large numbers. The 
Magnoliaceae and Nymphaceae (Angiosperms) and the Ophio- 
glossacea, Equisitaceae and Lycopodiales (Pteridophytes) have 
very high numbers, although not a great many species have been. 
studied cytologically. Finally Winge” in 1917 has given an 
additional list in plants and has concluded from that and from 
Tischler’s list that the numbers in related species are in arith- 
metical progression,—e. g. the chrysanthemums with 9, 18, 27, 
36, and 45,—these arising by hybridization of species with like 
numbers; and that in general numbers occur in factors of 2 and 3 
(an idea similar to that of Enriques), the numbers 8 (2.2.2) and 
12 (2.2.3) occurring most frequently. 
A cursory survey of Tischler’s or Ishikawa’s list of numbers in 
plants and of my own list in animals is sufficient to show that very 
9P. Della Valle. 1909. Archivio Zologico, 4, p. 1-177. 
0G. Tischler. 1916. Progressus Rei Botanicae, 5, p. 164-260. 
4 Mitsuharu Ishikawa. 1916. The Botanical Magazine, Tokyo, 30, p. 404- 
448. 
120. Winge. 1917. C. R. Travaux du Laboratoire de Carlsberg, 13. 
