120 CARL D. LA RUE AND H. H. BARTLETT 
and this species had been shown by Stomps^ and De Vries^ to be less 
mutable than Oe. Lamarckiana. In the recently discovered mass- 
mutating species the number of mutations may rise to almost lOO 
percent of the progenies. 
The elementary species that have thus far shown mass mutability 
are both segregates from the collective species that passes in our floras 
as Oenothera biennis. True Oe. biennis seems to be found in America, 
but the records in regard to its occurrence have not yet been published. 
It is therefore not incorrect to state that the species (in the narrow 
sense) is definitely known only in Europe, where it occurs as an in- 
troduced weed. The name Oe. biennis has been applied correctly by 
De Vries and Stomps, but very loosely indeed by American geneticists, 
with the result that the literature is considerably confused. Oe. 
Reynoldsii and Oe. pratincola are two, among a number of segregates 
from the collective species of the floras, that have been described and 
named^ for the purpose of keeping a clear record of the genetical ex- 
periments that are being carried out with them. They are not recog- 
nized in current systematic works. 
The first paper dealing with Oenothera Reynoldsii^ was written 
before any mutation crosses had been made. It was therefore only 
natural to suggest that the whole series of mutations to which it was 
giving rise were probably Mendelian recessives. Work on the closely 
related segregate Oe. pratincola shortly afterward disclosed the fact 
that the mutations characteristic of mass mutation were not Mendelian 
recessives, but showed matroclinic inheritance in crosses with their 
parent form.^ It has now been determined that the first suggestion 
in regard to the mutations of Oe. Reynoldsii was entirely erroneous, 
since they likewise show matroclinic inheritance. Although the 
special purpose of this paper is to present the data in regard to matro- 
clinic inheritance, there is one other striking discovery which it is 
possible to announce at this time, namely, that in Oe. Reynoldsii, as 
3 Stomps, Theo. J., Mutation bei Oenothera biennis L., Biol. Centralbl. 32: 
521-535. 1912; Parallele Mutationen bei Oenothera biennis L., Ber. Deutsch. Bot. 
Ges. 32: 179-188. 1914. 
4 De Vries, H., The Coefficient of Mutation in Oenothera biennis L., Bot. Gaz. 
59: 169-196. 1915. 
^ Bartlett, H. H., Twelve Elementary Species of Onagra, Cybele Columbiana i: 
37-56. 1915. 
6 Bartlett, H. H., Mutation en masse, Amer. Nat., 49: 129-139. 1915. 
^ Bartlett, H. H., Mass mutation in Oenothera pratincola, Bot, Gaz., 60: 425-456. 
1915. 
