332 BOTANICAL GAZETTE [APRIL 
crosses between two distinct types of wheat-macaroni (Triticum 
sativum, var. durum) and bread wheat (Triticum sativum, var. 
vulgare), which gave seeds much reduced in size and shrunken in 
appearance as the immediate result of cross-pollination. The 
smaller size and poor development of the seeds were due to the 
condition of the endosperm. The embryos were fully developed, 
however, and the first generation hybrid plants grown from these 
seeds were in some cases distinctly larger than either parent. 
This evidence of heterosis was shown in an increase in height of 
plant.4. If this hybrid vigor were due merely to a physiological 
stimulation of cell division it would seem that the endosperm tissue 
would be stimulated in the same way and show an increased 
development. On the view that heterosis is due to a bringing 
together of the greatest number of different favorable growth 
factors, these results would be easier to understand if it be assumed 
that the aggregated factors were favorable to the growth of the 
first generation hybrid plant but not to the hybrid endosperm. 
Cases of this kind in wheat, which may be rare, however inter- 
preted, would certainly argue against the origin of endosperm 
fertilization as an adaptive process. 
CONNECTICUT AGRICULTURAL EXPERIMENTAL STATION 
New Haven, Conn. 
LITERATURE CITED 
1. ANDRONESCU, D. I., The physiology of the pollen of Zea Mays with special 
regard to vitality. Publ. Depart. Agric. Kingdom of Roumania. 1915- 
2. Cottiys, G. N., and Kempton, J. H., Effects of rie on the 
size of seed in maize. U.S. Dept. ee Circular 124 
3. , A hybrid oe Tripsacum and Euchlaena. oa ‘Wash. Acad. 
Sci. 4:114-117. 19 
re Sabie ogenesis. > nae Heredity 7:106-118. 1916. 
5- CoRRENS, C., Bastarde zwischen Maisrassen, mit besonderer Beriick- 
ahdeun: der Xenien. Bibliotheca Bot. 53:1-161. 
Igor. 
6. Coutter, J. M., and CHAmBertarn, C. J., Morphology of angiosperms- 
7. DAR wie, Coane ES, The effects of cross and self-fertilization in the vege 
sis ‘ibiedites London. 1876. 
+ In so 
the increase in height was shown by actual measurements; 
in others, shaetvation showed that the plants were at least as well developed as the 
parents. 
