192 BOTANICAL GAZETTE [SEPTEMBER 
TON (30) in Thalictrum, Calycanthus, and Richardia. ALLEN’S 
extensive earlier paper on Lilium (1) should also be mentioned. 
Although, in such cases as Lilium, both accounts of reduction are given 
for the same form by different authors, yet the evidence from such 
forms as Nephrodium on the one hand, and Tradescantia, Oenothera, 
and Fucus on the other hand, makes it very difficult to deny that both 
methods occur. A comparison of a wide range of forms whose reduc- 
tion phenomena show many differences, will doubtless lead finally 
to an explanation of the nature and meaning of these differences. It 
is very evident that the time has passed when all the accounts of 
reduction in plants can be brought under a single scheme. The task 
of the future will be to interpret the meaning of the differences 
observed in various forms. Are they matters merely of cell mechanics, 
or are they related to hereditary processes? It is not impossible 
that correlations will be found between the method of reduction in an 
organism and its type of hereditary behavior. In other words, the 
phenomena of reduction and the distribution of elements during 
meiosis may condition to some extent the hereditary behavior of a 
plant or animal. This is already known to be the case with sex in 
insects. But it does not seem worth while entering into such theoret- 
ical possibilities on the basis of our present knowledge. 
The fact that in this Oenothera hybrid the number of chromosomes 
in the pollen mother cells is the sum of those which enter the fusion 
nucleus at the time of fertilization, is to me clear evidence that each 
chromosome in the germ cells is the genetic descendant of one of the 
chromosomes in the fertilized egg. The work of various investigators 
seems to have established the genetic continuity of chromosomes from 
generation to generation of individuals. ‘The manner in which the 
chromosomes are distributed during reduction in this Oenothera 
hybrid clearly shows that they behave as individuals at this time. 
Witson’s recent account of the supernumerary chromosomes ei 
Metapodius (37), a genus of Hemiptera, shows certain points © 
resemblance to the condition in Oenothera. WILSON finds that 
certain chromosomes (the idiochromosomes) may be present in duplt 
cate, or may even have several representatives in the cells of certain 
individuals, which nevertheless show no external difference> ” 
number of chromosomes being fixed for any individual, but vary 
