GENETICS: T. H. GOODSPEED 
345 
ployed in which self -fertilized seed of 'Nic. tahaccum Cuba' was simi- 
larly treated. Three types of seed were isolated, according to this 
method, from the parthenocarpic fruits. First, seed which consisted of 
nothing but empty seed-coats normal in structure and completely filled 
out. Second, seed of the first type which contained traces of endosperm 
but no embryos.^ Such endosperm tissue occurred as a sheath of cells 
lining the seed-coat or as a mass of cells at one end of the seed, the con- 
tents of which was rich in starch. These first two types were small 
seeds. The third type of seed isolated was identical with the self-polli- 
nated seed both in size and in the possession of normally developed 
endosperm and full sized embryos. Seeds of type one were overwhelm- 
ingly in the majority in every case and the total number of seeds shown 
to be in every yay normally matured, either by examination under the 
microscope or by the fact that they produced normal seedlings, was 
approximately thirty-five. They were produced, along with empty 
seeds and seed containing endosperm only, in approximately equal 
numbers in the nine parthenocarpic fruits. Four seedlings are matur- 
ing normally and are of fair size from nine seeds which were germinated 
out of a total of eighteen seeds available for germination. The eighteen 
seeds represent the proportion of the fifty undoubtedly viable seeds not 
used in the bleaching test. 
We may conclude, then, that parthenocarpy is of frequent occurrence 
in ^Nic. tahaccum Cuba' and that parthenogenesis, employing the term 
to mean the production of viable seed without pollination (cf. Wink- 
ler^), is also peculiar to this variety of N. Tahacum. With these un- 
usual phenomena manifesting themselves during this first year of culti- 
vation in our cultures I feel that there is a possibility, at least, that 
after further cultivation here parthenogenesis and parthenocarpy may 
become more nearly equal in the frequency of their occurrence. The ex- 
perimental results above described should furnish a partial confirma- 
tion of those reported by Mrs. Thomas for her experiments on ^Nic. 
tahaccum Cuba.' Nothing that has been said, however, must suggest 
that I desire to confirm her general results on the basis of which she 
concludes that parthenogenesis is peculiar to Nicotiana species in gen- 
eral. It must, on the contrary, be emphasized that our experiments, 
with all other species and varieties of tobacco, and those of a number of 
other investigators, point to exactly the reverse conditions and that we 
have no reason to suppose that parthenogenesis has ever before occurred 
in our cultures. I have no suggestion to offer, at the present time, as 
to the possible origin of this Nicotiana tahacum variety which exhibits 
