GENETICS: T. H. GOODSPEED 341
Conclusions.-In normal animals the circulation possesses the ability
to get rid readily of a surplus of dextrose injected intravenously. In
the absence of the pancreas this ability of the circulation is impaired.
This ability can be temporarily restored by an intravenous injection of
a pancreas emulsion.
Furthermore, an intravenous injection of a pancreas emulsion is cap-
able of reducing the hyperglycaemia due only to depancreatization to a
normal level of the dextrose content of the blood.
As to the nature of the factors which may constitute the ability or
inability of the circulation to get rid of a certain degree of surplus of
the dextrose content of the blood, we are not willing to discuss it at this
stage of our investigation. We are rather bent upon seeing how many
more facts we shall be enabled to bring to light on the basis of the
hypothesis which set us to work on these problems.
PARTHENOCARPY AND PARTHENOGENESIS IN NICOTIANA
By T. H. Goodspeed
DEPARTMENT OF BOTANY, UNIVERSITY OF CALIFORNIA
Preaente to the Academy. April 19, 1915
The occurrence of parthenogenesis in the genus Nicotiana has, in gen-
eral, been considered to be a negligible factor so far as the interpretation
of breeding experiments with tobacco is concerned. The only outstand-
ing instance in which castrated or mutilated tobacco flowers have
yielded viable seed is to be found in a report describing the experiments
of Mrs. R. H. Thomas.' Her experiments, apparently conducted with
due regard to the various sources of error, indicate that for her cultures
parthenogenesis in various species and hybrids of Nicotiana is of fre-
quent occurrence. Conflicting evidence is furnished by the experi-
ments of others. Thus, Howard,2 following experiments which involved
the emasculation of over 5000 flowers on many strains of Indian To-
bacco, found but five capsules containing seed and in only two cases was
it shown that this seed was viable. Hartley3 obtained two capsules of
seed 'by treating fully receptive stigmas with magnesium sulphate,' em-
ploying in his experiments flowers of 'Cuban Tobacco (Nicotiana Taba-
cum).' The seeds thus produced proved, however, to be nothing more
than empty shells. Further, East4 and Wellington5 claim that hybrid
seed, produced by crosses between certain species of Nicotiana, has given
plants 'like the mother species and also true hybrids,' plants 'like the
mother species and no true hybrids,' and that this seed gave 'no true
hybrids on one occasion but did produce true hybrids on other occa-