are undergoing investigation. At Cornell University, beans, 
corn, morning-glories, and cereals are being studied; while at 
Columbia University, students are analyzing the hereditary com- 
position of the little banana or pomace fly, of which there are 
over two hundred varieties. At Cold Spring Harbor, L. I., numer- 
ous studies on various plants, animals, and man are underway, 
while at the University of Wisconsin, soy beans, pigeons, dogs, 
etc., are being investigated. 
In peas, over thirty of these units have been isolated, some 
of which are of commercial importance, such as those for tallness 
and dwarfness, blunt pod, parchmented and non-parchmented 
pods. In tomatoes, color inheritance has been fully worked out 
at the New Jersey Experiment Station. An authoritative sum- 
mary of the studies on color inheritance in animals, — pigs, cats, 
dogs, cattle, horses, guinea pigs, rats, etc.— has been appearing 
in The Journal of Heredity. 
Heredity units of commercial importance have been isolated 
for castor beans as well as for many other plants. In corn, as 
many as thirty units or factors are known, while in the banana 
fly over one hundred have been determined. In some plants, 
crosses between certain varieties (not all) have given increased 
productivity in the first hybrid generation, and in the case of 
corn, walnuts, and tomatoes, the use of first generation (F t ) 
crossed seed is commercially important in increasingthe crop. 
(See Figs. 5 and 6). 
Among books on plant breeding and genetics, A. D. Darbi- 
shire’s “Breeding and theMendelian Discovery’’ is very readable 
to a laymen, and authoritative. Castle’s “Genetics and Eugenics’’ 
will appeal to the more practically inclined. More specialized 
treatment is to be found in books by Professor Morgan and his 
co-workers. 
In a former Leaflet (Series III, Nos. 10 and 11), directions 
are given for carrying out plant-breeding experiments in one’s 
own garden— a field capable of affording much pleasure and 
some profit. 
Orland E. White. 
