ANATOMY AND PHYSIOLOGY IOI 
insects; thus there are as 
many as 17,000 on each an- 
tenna of a blow fly (Hicks). 
The male of Welolontha vul- 
garis, Which seeks out the 
female by the sense of smell, 
has according to Hauser 39,- 
000 pits on each antenna, and 
the female only 35,000. Pits 
presumably olfactory in func- 
tion have been found by 
Packard on the maxillary and 
Fic. 134. 
labial palpi of Perla and on 
Longitudinal 
tiewcerc: “oO; the..cockroach ..,4a1 
Periplaneta americana. 
ula; h, 
Rath has described four kinds sensory 
faire 
of sense hairs from the two 
rf lomesticus. 
Vom aomesticus 
hypodermis; mn, nerve; ms, non- 
section of a portion of a 
appendage of a cricket, Gryllus 
, bladder-like hair; c, cutic- 
sense cell; sh, sensory 
After vom Ratu. 
Longitudinal section of apex of 
palpus of Pieris. c, cuticula; h, 
hypodermis; m, nerve; ss, scales; 
sc, sense cells.—After vom Ratu. 
larger of the four caudal appen- 
dages of a cricket, Gryllus; some 
of these (Fig. 134) may be olfac- 
tory, though possibly tactile. The 
same author found on the terminal 
palpal segment in various Lepidop- 
tera a large flask-shaped invagina- 
tion (Fig. 135) into which pro- 
ject numerous chitinous rods, each 
a process of a sensory cell, which 
is supplied by a branch of the prin- 
cipal palpal nerve; these peculiar 
organs are inferred to be olfactory. 
The chief reason for regard- 
ing these various end-organs as 
olfactory is that they appear 
from their structure to be better 
adapted to receive that kind of 
an impression than any other, so 
