is] 
who thought the fluid to be only the 
blood of the insect; the glands opening 
between the prothorax and head and 
between the mesothorax and metathorax 
in dytiscidae, of which the nature of the 
secretion has been somewhat studied by 
Plateau® ; the anal glands of Brachinus 
and other carnivorous coleoptera, the 
explosive mode of whose discharge in 
Brachinus has given rise to its popular 
English name of bombardier, for the 
literature of which I refer to Leydig’® 
(p. 46-49), and to a late paper by 
Rougement* ; the cornicles of the sixth 
abdominal segment of aphidae, which 
are supposed to pour out a sugary mate- 
rial sought by ants, but which material 
Witlaczil® writes, in a paper to which 
I will refer for further literature of the 
anatomy of aphidae, comes from the 
anus of these insects ;* the sacs, proba- 
bly glandular in function, found by 
Hagen* upon the larvae of certain neu- 
roptera; the odoriferous glands of hem- 
iptera mentioned by Landois*® and others ; 
the scent-glands which Aubé* mentions 
on the elytra and thorax of Eumolpus 
pretiosus ; the wax-secreting glands found 
on certain insects, treated of by Claus,” 
in 1867; and the odoriferous glands of 
phasmidae described by Seudder, in 
Psycue, v. 1, p. 137-140:—all these 
glands I pass by, giving reference only 
*Buckton,3’7 in vol. 1, of his Monograph of British 
aphides, discusses (p. 39-47) ‘‘honey dew” of aphidae as 
well as (p. 37-38) various waxy and silky secretions with 
which hemiptera cover themselves. I may add here 
that Gentry’s3 observation, in 1874, that young aphi- 
dae suck the secretion of the cornicles of older ones is 
anticipated by Morren,39 in 1836, and Morren adds to 
his statement “fait observé déja par Bonnet’?—fact 
already observed by Bonnet. 
92 PSITCHE. 
to some papers which will guide further 
to the literature of the subject, in order 
to come directly to forms of which the 
morphology is more interesting in this 
connection, or of which the function is 
not so well understood. 
An interesting economical provision is 
evident in the odoriferous tubercles of the 
larvae of Aftacus cecropia and in the urti- 
cating spines of Hyperchiria io. There 
is no waste of the secreted material by 
either of these larvae; it is sealed up 
until its use is necessary and then it is 
applied exactly where it will accomplish 
most. But what shall one say of the 
novel mode of avoiding waste, to which 
attention was called by Claus,* in the 
larva of the European chrysomelid, Lina 
populi? Along the dorsal side of this 
larva are rows of short black spines, not 
noticeably different from the spines often 
found on larvae of coleoptera, but if the 
larva is disturbed it. will suddenly press 
out upon the tip of each of the spines a 
spherical drop of milky liquid. Watch 
these drops fora moment. As the dis- 
turbance which has caused their appear- 
ance subsides, they become smaller, 
sometimes suddenly, sometimes gradu- 
ally, but always in unison, until finally, 
when the larva no longer feels itself in 
danger, the drops entirely disappear: 
the fluid has been drawn back into the 
spines to be used again-in case of need. 
Claus has suspected that salicylic acid 
exists in the secretion from the larva of 
Lina populi, which is very probable, since 
the larva feeds upon leaves of Salia and 
Populus, that contain salicin. of which 
