86 RESULTS FROM GIPSY MOTH PARASITE LABORATORY. 



days. Before molting it attains a length (jf nearly if not quite 2 

 nun., for some larva? were found, evidently nearly full-sized, about 

 1.7 mm. long. It now differs considerably in appearance from newl}^ 

 hatched larva^, as a comparison of figures 35 and 36 will indicate. 

 The head, being heavily chitinized, has remained the same size, but 

 the bod}' has grown until it is about five times as long as the head 

 instead of only twice as long, as at first. The tail has also increased 

 in size, but not proportionately to the growth of the body. Because 

 of this rapid growth the folds of the integument so noticeable in 

 newly hatched larvse have largely disappeared, but are still discern- 

 ible as slight creases, and afford the only means whereby the seg- 

 ments of the body may be distinguished. 



NOTES ON THE ANATOMY OF THE LARVA. 



The development of the viscera as made out in stained and mounted 



specimens is not without interest. Toward the end of the first instar 



the sericteries become the most conspicuous organs 



in the body, thus forecasting the prime importance 



of the cocoon-spinning habit as a protection during 



the pupal period. There is a pair of these silk 



glands which seem to start blindly in the first body 



segment and extend backward after branching once 



to the eleventh or twelfth segment. In reality, 



however, they are connected anteriorly with a 



minute tube which runs forward to the mouth. 



Fig. 37.— Limnerium The glaiids themsclves are also tubular "and com- 



vaiiihim: Mouth- posed of comnarativelv enormous cells, with large 



parts of lirst-stase , , • 



larva. Enlarged OVal UUcJei. 



about :25o times. ^he proctodanmi is also conspicuous and extends 



forward only to the anterior end of the twelfth 

 body segment. It is a thick-walled, ovoid organ, and although con- 

 tiguous with the posterior end of the mesenteron, it does not com- 

 municate therewith. At the anterior end it gives rise to four large 

 Malpighian tubules which extend forward into the ninth or even the 

 eighth segment. The anus ai3pears as a distinct opening at the end 

 of the twelfth segment on the dorsal side, thus proving that the tail 

 is a ventral outgrowth of the last segment. As the anus is distinctly 

 open, there is no reason wh}^ the secretions of the Malpighian tubules 

 may not be passed off into the blood of the host. 



The brain toward the end of the first instar is crowded partly out 

 of the head and becomes a consi)icuous organ of the first body seg- 

 ment. The same phenomenon takes place in regard to the infraoe- 

 sophageal ganglion. Twelve ventral ganglia may bo distinguished, 

 of which the first 5 are closely united to each other and to the infraoe- 

 sophageal ganglion, the following 5 being separated by commissures, 

 but the last 2 are also conjoined. 



