PROBLEMS OF HEREDITY, HORTICULTUKAL INVESTIGATION. 61 
"'heredity and the laws which it obeys. It is to be hoped that these 
indications will be at once followed up by independent workers. Enough 
has been said to show how necessary it is that the subjects of experiment 
should be chosen in such a way as to bring the laws of heredity to a real 
test. For this purpose the first essential is that the differentiating 
characters should be few, and that all avoidable complications should be got 
rid of. Each experiment should l)e reduced to its simplest possible limits. 
The results obtained by Galton, and also the new ones especially detailed in 
this paper, have each been reached by restricting the range of observation 
to one character or group of characters, and there is every hope that by 
similar treatment our knowledge of heredity may be rapidly extended. 
[Note. — Since the above was printed further papers on Mendel's Law have 
appeared, namely, de Vries, Rev. gener. Bot., 1900, p. 257 ; Correns, Bot. Ztg., 1900, 
p. 229 ; and Bot. Chit., Ixxsiv., p. 97, containing new matter of importance. Trof. 
de Vries kindly writes to me that in asserting the general applicability of Mendel's 
Law to " monohybrids " (crosses between parents differing in respect of one character 
only), he intends to include cases of discontinuous varieties only, and he does not 
mean to refer to continuous varieties at all. October 31, 1900.] 
Fig. 4.--0ncidium cbispum grandifloiium. [Jounial of UorlicuUurc.) 
