394 PSYCHE. 
larva of Papilio machaon, which he Says 
‘*protect it from its enemies, not by their 
strength, for they are hollow and delicate 
lobules, but by the stench which comes 
from them. Madame Merian calls it a 
pleasant odor (2d ed., pt. 1, n. 88) but 
I find it intolerable.” Since the time of 
Frisch many authors have described the 
osmateria of different species of Pupil’o, 
among them Karsten,” who described, in 
considerable detail, the anatomy of these 
organs in Papilio asterias. He says 
they discharge ‘‘a substance, strong- 
smelling like butyric acid, by which they 
scare away their enemies ; this substance 
reddens litmus readily, produces white 
clouds when brought near strong ammo- 
nia, has a somewhat biting acid but not 
unpleasant taste. Mixed with water, 
oil-like drops are seen under the mi- 
croscope; neutralized with ammonia 
it crystallizes.” The crystals ‘‘are 
not volatile upon raising the tempera- 
ture but decompose with disengagement 
of empyreumatically smelling vapors. 
Caustic baryta dissolves the acid, the 
salt crystallizes in groups of very fine 
needles.” For the anatomy and _his- 
tology of the osmateria of the larvae of 
Papilio I will refer to Karsten? and Kle- 
mensiewicz.* 
Each of the two caudal appendages of 
the larva of Harpyia consists of a basal 
tube which projects backward from the 
posterior end of the larva, but which 
can be turned somewhat upward and 
forward. Out of the tip of each of 
these basal tubes a reddish filament can 
be evaginated, which the larva, upon the 
approach of danger, curves above the 
body and waves with a trembling motion 
seeming often to whip the whole surface 
of its body. These threads or filaments 
are probably evaginated by internal 
pressure of the fluids of the body, but are 
retracted by muscles within them. There 
is some doubt whether these threads — 
are really glands, and Frisch* (1740, 
Theil 6, p. 18-19), who expected to find 
them odorous, writes that the odor 
‘‘must be very subtile and be only per- 
ceptible, for the most part, to insects 
hostile to this larva”; but, if these fila- 
ments are not glands, they have the 
same coarser anatomy and should be 
considered here. 
The earliest description of the evagi- 
nable caudal appendages of Harpy/a that 
I have seen is that by Goedart,” who 
says of them ‘‘This larva has two tails 
and when it is vexed, it will throw out 
from both tails a red rod or sting, which 
it bends back, and, as if mad, vibrates 
formidably, and draws it back in again.” 
Since Goedart’s time these appendages 
have been described by Réaumur,” 
Frisch™ (Theil 6, p. 18-19), de Geer® 
(Bd. 1, tab. 23, fig. 12), Bonnmet;™ 
Miiller™ (p. 28-30), Jérdens,*® Meckel, 
Klemensiewiez,*® and others. Some of 
these authors also describe the gland 
previously mentioned (p. 391), as open- 
ing upon the under side of the first tho- 
racic segment of the same larva, and 
Schiiffer,** in 1754, first shows the inti- 
mate relationship of this gland to evagi- 
nable glands found in the same position 
on larvae of other species, to the osma- 
teria of the larvae of Papilio, and in 
general mode of action to the evaginable 
glands of Mulachius. 
The evaginable organs of the imago of 
