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 CAUFORNIA 
Presented to the Academy, April 1 9, 1 9 1 5 
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,^ 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. Hartley^ obtained two capsules of 
seed 'by treating fully receptive stigmas with magnesium sulphate,' em- 
ploying in his experiments flowers of ' Cuban Tobacco {Nicotiana Taha- 
cum).^ The seeds thus produced proved, however, to be nothing more 
than empty shells. Further, East^ and Wellington^ 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- 
