3/0 NEUROPTERA CHAP. 



inent is arrested, the sexual organs not going on to their full 

 development, while other organs, such as the eyes, also remain 

 undeveloped ; the alimentary canal and its adjuncts occupy nearly 

 the whole of the abdominal cavity. The adult worker greatly 

 resembles except in size the young. Grassi considers that the 

 worker is not a case of simple arrest of developiient, but that 

 some deviation accompanies the arrest. 



The soldier also suffers an arrest of development in certain 

 respects similar to the worker ; but the soldier differs in the im- 

 portant fact that the arrest of the development of certain parts 

 is correlative with an extraordinary development of the head, 

 which ultimately differs greatly from those of either the worker 

 or of the sexual males and females. 



Soldier. All the parts of the head of the soldier undergo a 

 greater or less change of form ; even 

 the pieces at its base, which Connect 

 it by means of the cervical sclerites 

 with the prothorax, are altered. The 

 parts that undergo the greatest modi- 

 fication are the mandibles (Fig. 233, 

 B) ; these become much enlarged in size 

 and so much changed in form that in 

 a great many species no resemblance 

 to the original shape of these organs 

 can be traced. It is a curious fact that 

 the specific characters are betterexpressed 

 in these superinduced modifications than 

 they are in any other part of the 

 organisation (except, perhaps, the wings). 

 The soldiers are not alike in any two 

 species of Termitidae so far as we 

 know, and it seems impossible to ascribe 

 the differences that exist between the 

 FIG. 233.-The pairs of mandi- soldiersof different species of Termitidae 

 bies of different adult indi- to special adaption for the work they 



viduals of Termes sp. from T /> c< i ,i_- 



Singapore. A, Of worker ; have to perform. Such a suggestion is 

 B, of soldier ; c, of winged justifiable only in the case of the Nasuti 



male ; D, of winged female. ,. _ . N , . , , , 



(Fig. 234, 1), where the front of the head 



is prolonged into a point : a duct opens at the extremity of 

 this point, from which is exuded a fluid that serves as a cement for 



