PHYSIOLOGY OF THE IXVERTEBRATA. 45 



former secrete the silk-like material in which the larvee invest 

 themselves on turning into the pupal state. 



(lo) The Neuroptera. — In this order the mouth parts are 

 masticatorv, althouofh sometimes also suctorial. The aliraen- 

 tary canal is somewhat similar to that of the Lcpidoptcra. 

 There are eight free Malpighian tubules. 



(ii) The Hijincnoptcra is the order to which bees, waspg, 

 and ants belong. The mouth parts are for biting (ants), and 

 licking (bees). The labial palps are long and slender ; '• there 

 are two large paraglosste, and between them a median, annu- 

 lated, setose, cylindrical organ proceeds, which either repre- 

 sents the lingua, or is an independent prolongation of the 

 ligula. FandionaJly this organ is a tongue, and cnaUcs the 

 hce to lap up the honey on which it feeds. The mandibles and 

 maxillae are employed as cutting and modelling instruments, 

 but appear to have little or nothing to do with mastication, 

 properly so called." 



In the bee the mouth opens into a slender cesophagus, 

 which extends the whole length of the thorax, and at whose 

 posterior end it dilates into the large honey-bag (Fig. 8). 

 Before any honey passes into the stomach the so-called 

 valve (t)* must be withdrawn by a special action. The 

 '' valve *' then returns to its usual position, and thereby 

 converts the crop (li) into a sj)ecial receptacle for collecting 

 nectar until the bee reaches its hive. In the crop the nectar or 

 honey undergoes a change which prevents it (to a certain extent) 

 undergoing acetic fermentation. When the bee reaches its 

 hive the honey is regurgitated into waxen cells. The stomach 

 ■or chylific ventriculus (c) is very long and leads into a short 

 intestine (f), and then into a wide, distensible rectum (7). 



The poison of the Hymenoptera is a fluid containing formic 

 acid (H.COJ, which is secreted by a gland and retained in a 

 receptacle connected with the sting. The sting is nothing 

 more than a modified ovipositor.f In the larval bee the 



* Vide next chapter. 



t See Lacaze-Duthiers'ri JiechercJiei sur Varmure yeiitale femelle des 

 Jmedes. 



