30 Psyche [February 
Horace Donisthorpe. The discovery of this second species of 
Prodiscothyrea indicates that the members of the genus, like the 
species of Discothyrea, belong to a widely and discontinuously 
distributed and very ancient, hypogeic relict fauna, all the 
components of which are very rare and evidently on the verge of 
extinction. 
ANTHOCYANIN IN PTEROCOMMA SMITHIAZ (Mon.). 
: By RW. GrasEr, 
Bussey Institution, Harvard University. 
Pterocomma smithie (Mon.), an aphid, found on the stems and 
twigs of willow trees, contains a red pigment which seems to be 
localized in the cytoplasm of the fat cells. 
The pigment is soluble in water and alcohol, but especially in 
hydrochloric acid. A large number of aphids were rubbed up 
in a mortar with a few cubic centimeters of !/1) molecular HCl. 
This solution was then poured into a test tube and placed in a 
water bath for ten or fifteen minutes to facilitate the extraction of 
the pigment. After this, the liquid which became an intense dark 
red was filtered. If a few drops of 26 per cent. ammonia are now 
added the solution becomes blue or bluish green. On adding 
more and more of the alkali, a light green color appears, gradually 
passing to yellow. The reaction may be reversed at any point by 
adding HCl. If, after obtaining the yellow color with the alkali, 
one adds enough '/1) molecular HCl to the liquid the yellow will 
gradually pass back to the light green and bluish green. 
These color reactions very strongly suggest the anthocyanins 
found in plants. Anthocyanins form red pigments with acids 
which turn blue on the addition of ammonia. I suggest the fol- 
lowing possible series of reactions which might account for the red 
pigment in the aphids. The aphids suck up the hydroxyflavones 
from the plants! together with the sap. The hydroxyflavone is 
then reduced to anthocyanin in the body of the insect and later 
converted into the red pigment. The red pigment is deposited in 
the fat cells and may function as a respiratory pigment although 
this is not at all likely. 
.1Tests showed anthocyanin to be absent in twigs of willow. 
