OENOTHERA MUTANTS WITH DIMINUTIVE CHROMOSOMES 523 
striking similarity of the young rosettes, in the red sepals, deep yellow 
petals, quantities of seemingly good pollen produced, long seed-capsules, 
color and shape of the leaves. They differed chiefly in height and 
branching habits. If the reader will compare the C.S.H. and New 
York Botanical garden type with de Vries's photographs, their dis- 
similarity with respect to the latter character will be apparent at 
once. The C.S.H. mutant is found in cultures of 0. Lamarckiana 
X O. Lamarckiana (also among ofTspring of 0. lata X O. Lamarckiana 
and 0. lata, selfed), while it is quite possible that de Vries's ruhrinervis 
is produced by selfed Lamarckiana. If one is inclined to believe that 
de Vries's ruhrinervis is the product of inbred Lamarckiana and the 
C.S.H. type the result of crossing one Lamarckiana individual with 
another, unrelated Lamarckiana, one should not overlook the fact 
that de Vries also obtained the Amsterdam type from 0. lata X 0. 
nanella, O. lata X O. hrevistylis, 0. nanella X 0. brevistylis, 0. scin- 
tillans X 0. nanella, O. lata, 0. ohlonga, etc. 
Since Gates found 14 chromosomes in ruhrinervis and since the 
plants in which he made these counts were also grown in America, it 
would be instructive to learn whether they duplicated the vegetative 
characters of de Vries's form throughout, or whether they also were 
modified individuals of the same type as the New York Botanical 
Garden and Cold Spring Harbor mutants. Had the small chro- 
mosome been present in the somatic cells of the plant which Gates 
studied as it was in the Amsterdam mutant, it is not probable that it 
would have been overlooked. It will be borne in mind, of course, 
that it has not yet been shown that all plants having the same type of 
vegetative characters as de Vries's mutant have 14+^ chromosomes; 
for, thus far, the somatic chromosome number of but one Amsterdam 
ruhrinervis has been reported. It may be that the small remnant 
merely chanced to be handed down from the lata mother of No. 6082 
without affecting the characters of the ruhrinervis offspring. 
Summary 
I. The primary object of this series of three papers, of which the 
present report is the first, is to discuss, in the light of the Cold Spring 
Harbor and Louvain studies of somatic chromosome number in Oen- 
othera Lamarckiana and its derivatives, certain theories and conclusions 
which Gates has advanced from time to time, and which Gates and 
Miss Thomas have based upon the results of their investigations. 
