72 BOTANICAL GAZETTE [JULY 
The author calls it the “conica-type,”’ because of its characteristic thick 
conical buds. It has been Soenibed already as “‘velutina’’ in the same author’s 
papers on “twin hybrids.’”” While O. muricata was incapable of such com- 
plete analysis as was given to biennis, owing to the fact that many of its hybrids 
are weak or sterile, several crosses in which muricata was used as the seed 
parent show that in this species also there is a morphological type determined 
by the egg cell different from that carried by the pollen cell. The seed-borne 
type of O. muricata is called by DEVRiEs the “‘frigida-type.”’ It comes to 
light in crosses of O. muricata as seed-parent with “ biennis Chicago,” Hookert, 
and strigosa pollen parents. It has tall, ates nearly glabrous stems, but 
little branched, with flowers resembling O. bien 
ese results are of unusual theoretical Gas and the study of 
double reciprocal hybrids will no doubt lead to the — of other instances 
in which different potentialities are borne by eggs and sp 
HonInc” has made a statistical study of the “twin hybrids” of O. Lamarck- 
iana and O, rubrinervis in the attempt to identify the velutina with rubrinervis 
and Jaeta with Lamarckiana. He finds in nearly all the morphological char- 
acteristics which differentiate the twin hybrids a fairly close parallel with the 
convinced by these facts that O. Lamarckiana and O. rubrinervis are both of 
hybrid nature, each possessing in the latent state the characters of the other. 
He offers no suggestion, however, as to how it happens that this hybrid nature 
fails to ca itself when O. Lamarckiana and O. rubrinervis are self-fertilized. 
ZEIJLSTRA™ has discovered that the most common form of O. nanella is 
er , a Micrococcus which forms zoogloea-like masses in the cavities 
of the cells. The diseased plants have a characteristic appearance which 
em easily detected even in their early stages. Normal (that is, 
undiseased) O. nanella has also been discovered, but much more rarely, and the 
latter has never fruited. It is suggested that the true normal O. nanella may 
have been frequently overlooked, owing to its resemblance to O. Lamarckiana. 
How it happens that all the offspring of the diseased O. nanella are of the 
parental t needs investigation. The author points out two alternative 
explanations: namely, that this diseased strain of O. nanella inherits a suscepti- 
ility to the attack of the Micrococcus, or that the germ cells are themselves 
infected by the parasite. In the latter case a microscopic study of the germ 
cells should perhaps detect the presence of the Micrococcus.—Gro. H. SHULL. 
10 HONING, J. A., Die 2 amen der Oenothera Lamarckiana. Zeit. f. Ind. 
Abstam. Vauk 4: ‘ik Sigs. 10. 1911 
 ZEIJLSTRA, H. H., Oenothera nanella DeVries, eine krankhafte Pflanzenart. Biol. 
Centralbl. 31:129-138. figs. 5. 1911. 
