1886. j Entomology. SII 
less likely that artificial digestion could be successfully performed 
than in the case of higher animals. Nevertheless, there are cer- 
tain ways in which the problem could be attacked with every 
prospect of success. (1) There are many larve which eject a 
green fluid from the mouth, and this fluid has the same spectrum 
as that of the blood (in the instance examined). It is probable 
that such a solution might be made by artificial digestion. (2) 
The blood of some large larve in which the pigments passed 
into the hypodermis cells might be investigated at various times 
after their first meal, when more extensive fluctuations might be 
witnessed.—Z, B. Poulton, Trans. Ent. Soc., London, 1886. 
TuE Fruip EJECTED BY NOTODONTIAN CATERPILLARS.—This 
defensive fluid, says Mr. Poulton (Trans. Ent. Soc. London, 1886, 
157), as is well known, is ejected from a transversely placed 
aperture on the ventral surface of the prothorax immediately be- 
affecting litmus-paper in the most marked manner. During the 
last summer he found that the fluid causes violent effervescence 
when allowed to fall upon sodium bicarbonate, and has proved 
y the reduction of silver nitrate) that the fluid is formic acid. 
The smell is also quite characteristic, and affords an indication of 
the larger Proportion of acid present in the secretion. Fle also 
States that the freshly-made and moist cocoon of Dicranura 
vinula is powerfully acid to test-paper. : 
“In September, 1885, I found a few larve of D. furcula on wil- 
low, near Visp, in Switzerland, and I examined them to see if 
they also would eject a fluid when irritated. It was at once 
obvious that the aperture was present in’the same position as in 
D. vinula, but as the larve did not eject any fluid I applied gen- 
tle pressure (for this is often necessary in the case of D. vinula). 
To my reat surprise a complex form of “ gland” was instantly 
everted through the aperture, consisting of six diverging pro- 
cesses of a light green color, divided into two groups of three 
ach. It will be very interesting to investigate the young stages 
hss D. vinula in the light of this observation, for it will then be 
ble and has fallen back iato the condition with which all such 
Structures must have begun—a simple secretory involution dis- 
