( xciii_) 
secretions have yet to be discovered ; the suggestion (so much 
insisted on by Haase) that these juices are directly derived 
from those of similar quality in the food-plants of the larve 
arising from the long-known circumstance that some of the 
food-plants of species in the protected groups are of an acrid 
or poisonous character, such as (e.y.) Asclepiads in the case 
of many Danaine, and Aristolochia in that of the inedible 
forms of Papilionine. No doubt, too, the fact that the 
unpleasant qualities are very often fully developed in the 
larve of the distasteful species—as I have found with Danais 
chrysippus and various Acreee—lends some weight to the 
suggestion; but at present nothing approaching sufficient 
data can be brought forward respecting the actual food-plants 
to which the protected groups, in contrast to the unprotected, 
are thought to be restricted. It cannot be gainsaid, as Prof. 
Poulton has pointed out,* that the food-plants of many of 
the distasteful European moths do not belong to any 
poisonous or acrid category ; and his own and Mr. Latter’s 
papers on Dicranura vinula alone amply demonstrate what 
powerful acids can be elaborated by a larva which finds its 
food in such innocuous plants as poplar and willow. The 
supposed direct derivation of the nauseous juices from the 
plants consumed is thus plainly a matter that awaits investi- 
gation from both biological and chemical standpoints. 
(c.) The avoidance or rejection as food by insectivorous 
animals of the insects possessing malodorous or distasteful 
juices no longer rests merely on the negative evidence given 
by Bates, Wallace, Belt, and other competent observers, to 
the effect that in nature such distasteful forms are habitually 
neglected and unmolested; there is now much positive experi- 
mental evidence as to the manifest avoidance or disgust with 
which such species are left untouched, or thrown aside after 
tasting, when offered to domesticated or captive vertebrate 
animals that devour ordinary insects with avidity. The 
numerous experiments of this kind recorded by Butler, 
Jenner Weir, Weismann, Poulton, and Lloyd-Morgan, as 
* Proc. Zool. Soc. Lond., 1887, pp. 198, etc., and ‘‘ Nature,” 4th Nov., 
1897, p. 3. 
H 
