SOFT PARTS AND MECHANISM OF THE PROBOSCIS. 403 ‘ 
as such, although Leydig, and more recently Otto Rath [133], ; 
recognised their nervous character. ee 
Each end-organ consists of a very thin capsule of flat cells, 
loaded with dark-orange pigment granules. These cells are a 
part of the hypoderm, which is also similarly pigmented in the 
neighbourhood of the sete. Within the pigmented cells is a 
layer of eight or ten fusiform nerve-cells, in which the nerve- 
fibres terminate; these enclose a single large cell, the tricho- 
genic cell, which extends into the seta. The trichogenic cell 
is clear and transparent, or possibly filled with fluid; the 
nucleus is pressed to one side of the cell by what appears to be 
a large vacuole. The sheath of the nerve is continued as a 
thin membrane between the pigmented sheath and the nervous 
elements, and is apparently attached to the base of the seta. 
I am inclined to regard these organs as touch corpuscles. It 
is possible, however, they may be special organs of taste. I 
have sought in vain for organs of taste on the lips and ligula. 
Kiinckel d’Herculais describes and figures such organs on the 
ligula of Volucella, but I find no trace of any in the Blow-fly. 
The only organs which appear to me to have the character of 
organs of taste are on the maxillary palpi. The palpus receives 
a very large branch from the labial nerve, and numerous gang- 
lion cells exist in the interior of the organ, connected on the one 
hand with the nerve-fibres, and on the other, by numerous 
branches, with several layers of small cells which lie imme- 
diately under the skin, and are most numerous towards the 
extremity of the palpus. 
The sete on the palpus are of two kinds: large tactile sete, 
few in number; and small transparent sete, which are very 
numerous. The large sete have similar organs to those con- 
nected with the setz of the labial lobes. The small cells which 
underlie the cuticle give off processes which enter the fine 
sete ; and these are either grooved or hollow, and contain a 
substance which stains deeply with carmine and logwood. In 
this character they differ from all the other sete I have 
examined. They appear to act as capillary tubes, which 
become filled with the staining agent. It is well known that 
