C. Hay Murray 
307 
bug is all that represents the theoretical chain of segmentally arranged 
nerve centres. It is rather a large mass, and is laterally bilobed, giving off 
nerves to the thoracic appendages. From its posterior end goes off the 
twin trunk which supplies the rest of the body. After the thoracic ganglion 
the nerve cord, which, although double, yet has the two cords so closely 
approximated as to appear’single, has no visible ganglionic swellings. 
Along its length it is in close proximity to fat cells which almost obscure 
it in a well-fed bug, while in one which has had a long fast, the nerve 
cord is easily distinguished. 
The structure of the eye has not yet been investigated by the writer, 
because repeated trials with different fixatives under varying conditions 
either rendered the chitin too brittle or else did not fix the contents of 
the eye. From a “ paraffin embedding ” point of view, the bed bug is 
very difficult to manipulate, as the chitin is so impervious to reagents. 
The writer after many failures only got results by slicing off a portion 
of the side of the abdomen after partial fixing so as to enable the 
reagents to penetrate. Without this the bug was never properly 
imbedded. Henning’s solution, recommended in the Microtomist’s Vade- 
Mecum as good for softening chitin, was not conspicuously successful 
with this insect. 
The Pat Body. 
Since the bed bug has often to pass long periods without any pros¬ 
pect of a meal, we would expect to find its fat cells well developed. 
They are in great profusion and for the most part are found in two rows 
of irregularly shaped cell masses, arranged down the sides of the abdo¬ 
men. Their size varies greatly, according to the date of the last meal. 
Besides the lateral major masses, there are collections of what.are 
evidently fat cells round the heart and the nerve cord. 
The Stink Glands. 
Any one at all acquainted with bed bugs is aware that they can 
give rise to a most offensive smell. This is the secretion of a couple of 
glands (one on each side of the thorax), which open to the exterior on 
the metasternum. In the words of Messrs Douglas and Scott {The 
British Hemiptera, Part 1, page 2) : “ On each side (of the metaster¬ 
num) anteriorly near the coxa, is the orifice of the internal sac containing 
the matter which gives to so many of the Hemiptera their disagreeable 
smell.” These sacs vary very much in size. Occasionally they extend 
well down into the abdomen, and again they may be so minute as to be 
