EI? BOTANICAL GAZETTE [FEBRUARY 
were first found in O. pratincola. HUNGER” has recently recorded 
observations on selective mortality in the seeds of O. Lamarckiana 
which can only be interpreted as showing that the mutations of 
this species have decidedly a greater survival value than the 
parent form. 
It is often remarked that the Onagras are not most usually © 
found in undisturbed habitats with other native plants, but rather 
as weeds in fields and waste places, among the aliens of our flora. 
Wherever the soil is disturbed, as by plowing, road-making, 
excavating, they are frequently found in large numbers. They 
often dominate the flora on made land and on new railroad embank- 
ments, but are for the most part replaced by other weeds when the 
soil ceases to be disturbed at intervals. A fallow field which con- 
tains many Onagras for a season or two after cultivation is dis- 
continued will thereafter contain fewer each year. If again plowed, 
it will apparently be restocked by the germination of seeds 
which have lain dormant, perhaps for years. Selective mortality 
among dormant seeds might result in such a field being restocked 
with plants among which mutations would be unexpectedly 
numerous. : 
The most interesting fact shown by table XII is that the fre- 
quency of mut. xwmmularia cannot correspond with any Mendelian 
ratio except that of a tetrahybrid splitting in the ratio 255:1- 
In the case of a number of progenies, to be sure, the ratio of muta- 
tions to plants more nearly approximates the trihybrid ratio 63:1, 
but it has already been shown that in each such instance the high 
mutation ratio is associated with a low percentage of germination. 
When the ratio of mutations to seeds is dealt with, there is no case€ 
of an approximation to the 63:1 ratio. The data of table XII, 
recalculated, are stated in table XIII in such form as to show that 
no single progeny was large enough to prove that the 255:1 ratio 
might not be the true one. On the contrary, the data afford no 
reason to believe that the mutation ratio is 255:1. It may be 
because of the smallness of the cultures that no single progeny 
shows a significant deviation from this ratio. 
 HuncER, F. W. T., Recherches expérimentales sur la mutation chez Oenothera 
Lamarckiana, executées sous les tropiques. Ann. Jard. Buitenzorg 27:92-113- 1913- 
