; 34 



THE POPULAR SCIENCE MONTHLY. 



-ao 



m 



all tlie chatoyant dust, and to lay bare the transparent membrane 

 which it covered. 



Some Coleoptera, as the Larinus and the Polydrosus, become 

 unrecognizable when an awkward hand has stripped them of their 

 magnificent raiment ; the emerald robe and the curious designs 

 disappear, to give place to the dark coloring of the teguments. 



The circulatory apparatus of insects 

 (Fig. 15) comprises a dorsal vessel (or 

 heart), from which the ramifications 

 start that distribute the life-giving 

 fluid through the organization. The 

 nervous network (Fig. 1G) extends over 

 the ventral face of the animal in the 

 shape of two ganglionic cords which 

 come together under the digestive tube 

 to separate again into two branches. 

 The latter embrace the oesophagus like 

 a collar, and meet above it to inclose 

 the cerebral mass. 



As we have just seen, the nervous 

 system is specially localized in the ven- 

 tral region, while the seat of the circu- 

 latory apparatus is chiefly in the dorsal 

 region. This is almost the exact con- 

 trary of what is remarked in verte- 

 brates. 



*#-' The digestive apparatus (Fig. 17) is 



Fig. 15. CirculatoryApparattts of situated between the circulatory and 



the Cockchafer, ao, aorta: c, j_i j_ -i mi l 



,i,i D i . r the nervous networks. The respiratory 



dorsal vessel ; m, suspensory liga- _ * J 



ments of the wings. (Straus- orifices, which give passage to the air, 

 Durckheim, Anatomie comparee are distributed along the body. They 



des animaux articules.l ,, , .. , TT ., -. . 



are called stigmata. Upon them abut 

 the tracheae, tubes of an extreme tenuity, the interlacings of which 

 branch out through the tissues. 



The whole body of the insect is sensitive to touch, but the per- 

 ception of sensations takes place chiefly by hairs in direct relation 

 with the nervous system. These hairs are found more or less all 

 over the creature, but particularly upon the antennae and at the 

 ends of the palpi. 



The convenient arrangement of the eyes enables the insect to 

 see all around itself without making any motion. The length of 

 its view has not been precisely determined, but experiments seem 

 to show that it is not great. The part played by the ocelli is also 

 not clearly determined. In insects living in dark places, especially 

 in those strangely shaped ones that live in caves, the organ of 

 sight is atrophied, and is represented only by little swellings hav- 







