CENETICS: j. A. HARRIS 
317 
tozoa, one with and one without a sex chromosome; and that if a sper- 
matozoon of the former type enters an egg a female is produced. Since 
in artificial parthenogenesis no sex chromosome is introduced the par- 
thenogenetic frogs should be males. 
It will be of further interest to find out whether the spermatozoa of 
such frogs when used for the fertilization of eggs will give rise to normal 
offspring and to both sexes and it is my intention to carry the experi- 
ments if possible to a decision of this question. It is further of interest 
to study the number and nature of chromosomes in the spermatozoa 
of the parthenogenetic frogs. 
[Since the proof of this paper was read, another of the partheno- 
genetic frogs died, at the age of thirteen months. It was also a male, 
possessing well developed testicles of more than 1 mm. in diameter, 
and the typical pads on the thumb of the forelegs characteristic of 
the male.] 
'Loeh, J., Anm. J. Physiol., 3, 135 (1899); 3, 434 (1900). 
^Loeb, Artificial Parthenogenesis and Fertilization, Chicago, 1913. 
3 Pelage, Y., Paris, C. R. Acad. Sci., 148, 453 (1909). 
*Loeb, J., and Bancroft, F. W., /. Exp. ZooL, 14, 275 (1913); 15, 379 (1913). 
^ Dr. Uhlenhuth was kind enough to do this for me. 
DE VRIESIAN MUTATION IN THE GARDEN BEAN, 
PHASEOLUS VULGARIS 
By J. Arthur Harris 
STATION FOR EXPERIMENTAL EVOLUTION. COLD SPRING HARBOR, N. Y. 
Received by the Academy, April 25, 1916 
The extensive experience of experimental breeders with Phaseoliis 
vulgaris during the past fifteen years has yielded few cases of unques- 
tionable de Vriesian mutation. Such seems the most logical explana- 
tion of the origin of a race now under cultivation at the Station for 
Experimental Evolution. 
Among the plants which survived from a lot of 4286 morphological 
aberrant plants secured in a study of 238,015 seedlings in 1912 were 9 
which were distinguished from the remainder by producing only highly 
abnormal offspring in 1913. Practically without exception the 8000 
first, second and third generation offspring produced in 1913, 1914 and 
1915 were of a similar morphologically aberrant type. The same is true 
of a smaller culture of fourth generation plants grown in the greenhouse 
in 1915. 
In this race the whole morphological organizatioa of the seedling has 
apparently been changed. The new race is also characterized by a high 
degree of variabiHty. 
