INTERXAL AXATOMY. 37 



and ocelli {oc, oc'). The infra-oesophageal ganglion has 

 three pairs of nerves leading to the mandibles and first 

 and second pairs of maxillae, respectively. The sympa- 

 thetic, or vagus nerve (sm), starts from a ganglion resting 

 above the oesophagus, and connects with another ganglion 

 (sg) near the hinder end of the crop, nv is the nervous 

 cord and ganglia which extends along the ventral side of 

 the body ; ov, the ovary ; ov.l, the oviduct ; ov.f , site of 

 opening of the oviduct (the left oviduct is cut away) ; be, 

 the bursa copulatrix ; and sb, the sebaceous gland which 

 secretes the sticky fluid that fastens the eggs together. ^ 



We have already alluded to the muscular power of 

 locusts. This is so great in some insects that they 

 are able to leap forty times their own height ; and the 

 flea leaps, it is said, two hundred times its height. 

 They have also been known to lift ten times their own 

 weight, and one kind of beetle {^Geotrupes ste?rora- 

 rius), according to Newport, is able to sustain and 

 escape beneath a pressure of nearly five hundred times 

 its w^eight. Such facts are readily demonstrated in 

 the schoolroom. The secret of the insect's muscular 

 power lies in the extreme lightness and immense 

 strength of its tubular skeleton, its elastic power of 

 resistance to pressure, and the large surfaces afforded 

 for the muscles. Whatever difference, if any, there 

 may be in the quality of the muscles, it is only neces- 

 sary to examine the internal structure of an insect, 

 and see their disposition, and the way in which they 

 are attached to the skeleton, to understand that they 

 possess an enormous advantage over the muscles of 

 vertebrates. The greater comparative extent of the 



1 See First An. Rep. U. S. Ent. Com., 1877, p. 261. 



