174 NATURAL HISTORY OF WASPS. 
with a common lens, and unfailing in their applica- 
tion. To the central spine which supports this we — 
shall return, further on, in the female, where it 
appears in the modified form of the sting. 
The testes are placed symmetrically, deep within 
the body. They correspond to the symmetrical 
ovaries of the female, not only in their general out- 
line, but in the tubular arrangement of their internal 
structure. Like them, too, they run off into tracheal 
threads at the anterior extremity. Hunter* says 
that, while these glands are developed on both sides 
in the hornet, in the wasp usually only one is found. 
I have never examined these organs in a hornet; but 
in wasps I have generally found two glands, placed 
symmetrically, occasionally varying in size, and 
sometimes having tubular diverticula, or lateral 
pouches. 
The male organs are obtained for dissection with 
very little trouble. The wasp, as fresh as possible, 
should be gently pressed on the abdomen, and, as 
the strong horny scales protrude, they may be with- 
drawn by the aid of the forceps, brmging with them 
the testes and the end of the alimentary canal. The 
appearance of the specimen is not in any way injured 
by the careful removal of the organs in this manner. 
For a more particular examination, however, they 
must be removed from the abdomen in the same 
way as, and, on account of the smaller size of the 
male, with even greater precautions than, the organs 
of the female, which come next under consideration. 
For their demonstration we need the water-trough, 
* Hunter. Posthumous Works ‘On the Economy of Hornets and 
Wasps.’ Vol. I, pp. 79 and 90. 
