Volume I 
JANUARY, 1902 
No. 2 
VAEIATION AND INHERITANCE IN THE PAE- 
THENOGENETIC GENERATIONS OF THE APHIS 
"HYALOPTERUS TRIRHODUS'^ (WALKER). 
By ERNEST WARREN, D.Sc, Univoisity College, Londrm. 
[Received November 5, 1901.] 
(1) Material and Methods. 
Two years ago I made a preliminary investigation* on variation and inherit- 
ance among the parthenogenetic generations of Daphnia magna. In conformity 
with Weismann's views the individuals of the same parthenogenetic family ought 
to resemble one another very closely indeed, but this was found to be far from the 
case. The variability of the members of such a family was not very strikingly 
smaller than among sexually produced offspring. The intensity of inheritance, 
however, between offspring and parthenogenetic mother appeared very consider- 
able ; and with the data that were then available it seemed to be greater than 
with sexually produced young. 
The object of the present investigation was to test the conclusions which were 
drawn from the daphnia results, but the supposed high value of the parental 
correlation had lost much of its apparent significance by a wider acquaintance 
with inheritance among sexually produced offspring. 
Last July the great abundance of green-fly on some common columbines in a 
garden suggested that the Aqinlegia might prove to be a suitable plant for breed- 
ing purposes. A dozen large plants in pots were obtained fi'om a florist and placed 
on a table under an awning in a sheltered corner of a garden. One or two of these 
plants had plenty of Hyalopterus\ on them while the I'emainder were very nearly 
clean. I placed a few aphides here and there over the clean plants and these 
individuals soon settled down and became quiescent. 
* B. S. Proc. Vol. 65, 1899. 
t Monogmjih of the British Aphides, G. B. Buckton, Vol. ii. p. 114. 
Biometrika i 
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