1916] HOAR—STERILITY IN RUBUS 373 
Before leaving the general question in regard to the formation 
of sterile pollen, I should like to call attention to another phase 
upon which no great amount of work has yet been done. This is in 
regard to Mendelian research. BRAINERD (30), in one of his articles 
concerning hybrids of Viola, describes violets which he has culti- 
vated and which he knows to be hybrids from their external 
characters. BATESON (22) makes this statement: “Such an 
experiment raises the hope that sterility consequent upon crossing, 
the most obscure of all genetic phenomena, may become one of 
the possibilities of Mendelian research.” JESENKO (19), using a 
cross between wheat and rye, was able to obtain one hybrid plant 
with pollen mostly shrunken and sterile. After several artificial 
crosses he was able to obtain a second generation hybrid which was , 
apparently quite fertile. However, when he repeated the experi- 
ment on a larger scale, he obtained several first generation hybrids, 
but could obtain none of the second generation except through 
back-crosses. He now thinks that the first second generation plant 
which he obtained was of such a nature. Surron (20) also has 
done work in crossing varieties and species of cultivated peas, 
together with a wild pea of Palestine (Pisum humile), and his 
results have been confirmed by BaTEsON (22). Although he found 
the first generation hybrid to be either entirely or partially sterile, 
yet when he obtained second generation plants, he found them to 
be fertile. This may, perhaps, be explained by the fact that he 
used plants close in relationship and hence more compatible. 
Within a few months a study of pollen sterility has been made 
by BELtNc (15) in which he has attempted to show that certain 
ratios prevail. His work has been carried on in Florida, chiefly 
with 3 species of Stizolobium. The first, the Florida velvet bean 
(Stizolobium deeringianum Bort.), he states is of unknown origin, 
but is very commonly known as “a large ornamental tropical 
climber.” The second, the Lyon bean (Stizolobium niveum Rox- 
burgh), is commonly grown in the Philippines and elsewhere in 
South Asia. The Yokohama bean (Stizolobium hassjoo Piper and 
Tracy), which he takes for the third, is common upon the island of 
apan. He has worked more especially with these, but some 
work, though only with the first generation hybrid, has also been 
