ANTS. 



certain species (Last us niycr, Atta) may develop into workers. The 

 Dzierzon theory cannot, therefore, be rigorously extended to the ants 

 till this matter has been more thoroughly investigated. 



No complete embryological study of the ants has yet been under- 

 taken. The earliest account of the development of these insects is by 

 Ganin (iSfxj). lie studied the eggs of Lasius flai'us, Formica fuscu, 

 Mynnica Iwinodis and ruyinodis and Tctramorinm ccspitnin, and 

 described the formation of the amnion. This envelope, he maintained, 

 arises by delamination from the blastoderm, but as his investigations 

 were made before modern embryological methods were introduced, it 



is impossible to attach much importance 

 to his statements. Several years ago 

 Blochmann published two short papers 

 (1884, 1886) on the growth of the ovarian 

 egg, and the formation of the polar bodies 

 and blastoderm in Camponotus lighiperdus 

 and Formica fitsca. I have examined 

 some of the later stages of F. gnai'a and 

 find them to be very similar to those of 

 the bee (Ap'is, Chalicodoma) and wasp 

 (Polistes). The accompanying sketch 

 (Fig. 35) of a young embryo of F. gnara 

 is interesting as showing some of the con- 

 servative traits in the development of 

 ants. Not only are there distinct traces 

 of the antennae (not seen in the figure, 

 as the head is folded over the anterior pole 

 of the egg) and three pairs of thoracic legs, but there are also traces 

 of the abdominal appendages, although all of these disappear before 

 the hatching of the larva. The thoracic limbs and antennre again 

 develop in the larval stage, but the evanescent abdominal appendages, 

 with the exception of those that go to form the parts of the sting of 

 the adult, are mere vestiges, harking back, so to speak, to the legs of 

 ancient larval types like the caterpillar, or cruciform larva of the saw- 

 Hies or even to the Pakeoclictyopteroid ancestors of all insects. 



The larva emerges from the egg as a soft, legless, translucent grub, 

 usually shaped like a " crook-necked " squash or gourd, with a broad, 

 straight posterior and narrower, curved anterior end terminating in a 

 small but distinct head (Fig. 36). In some forms (Eciton, Parasyscia, 

 Lobopelta, etc.) the body is more cylindrical (Fig. 37). In all cases, 

 however, it consists of a head and thirteen more or less clearlv marked 



FIG. 38. Larva of Stig- 

 matonima pallipcs. (Origi- 

 nal.) a. Larva from the side; 

 b, flexuous hair enlarged ; c, 

 head from above. 



segments. 



Three of these belong to the thorax, the remainder to the 



