ANTS. 



-- P 



wall of the cocoon, draw .forth the young and strip the enveloping 

 cuticle from its body and appendages. The newly hatched ant which 

 has not yet acquired its deep adult coloration is known a^ a callow. 

 Owing to the absence of wings, the hatching of the workers is some- 

 what more easily accomplished than that of the males and females. 

 Uewitz (1878) has shown that the worker larva actually possesses mi- 

 nute histoblasts of these appendages, but they do not develop except in 

 certain abnormal individuals which I have called pterergates ( Fig. <>$). 



In ant larva? that do not spin 

 cocoons, development and hatch- 

 ing are, of course, considerably 

 simplified (Figs. 48 and 4'M. 

 In such species the adult larva 

 passes at once to the semipupa 

 stage after discharging the me- 

 conium. A worker receives the 

 black pellet in its mandibles, or 

 even pulls it out of the large in- 

 testine and deposits it on the ref- 

 use heap of the nest. The fact 

 that the cocoon is constantly pres- 

 ent in the most primitive ants 

 and as constantly lacking in large 

 groups of highlv specialized 

 forms, shows that it is an ancient 

 inheritance from solitary, wasp- 

 like ancestors. Certain Campono- 

 tine genera and subgenera ( Prc- 

 nolcpis, QicophyUa, Playiolcpis 

 and Colobopsis) always have 

 nude pupse, and in certain species 

 of Formica and Lasius the cocoon 

 may be present or absent in the 

 brood of the same colony or even 

 in the male and female pupae. 

 Janet (1896^) regards the sudden 

 elimination of the envelope in 

 these species as a mutation, or 

 saltatory variation. I have seen 



s 



9 /Tfl , 



--m 



FIG. 44. Anatomy of ant larva. 

 (Perez.) b, Brain ; >i, ventral nerve 

 cord ; o, oesophagus ; p, proventriculus ; 

 s, midgut (stomach) ; v, mass of sub- 

 stance to be excreted; r, rectum; m, 

 Malpighian vessel; g, spinning gland; 

 d. duct of same opening on labium ; 

 h, heart. 



the nude pupae of a Dolichoderine 

 ant (Iridomyrmex gciuitzi) in the Baltic amber (Lower Oligocene), 

 so that the complete elimination of the cocoon, in this subfamily at 



