A. 10. Camkron •">•> 



be dofinitely stated, but a reference to my "otes reveals the case of one 

 female which laid first eleven egj^'s and then proceeded to deposit two 

 more groups of twelve and nine. The probability is that even then 

 she had not finished. Perhaps ft)rty would be a very low estimate. 

 In an examination of a fertilised fen\ale about one hundred and forty 

 ova, of which twenty-two were ready for (»vi position, were discovered 

 in the effg-tubes and uterus. 



"iTltTl 



Hdhils of Jarra, (Juration of Ihe various larval stadia, 

 papal period. 



The behaviour of the larva within the epiderm of the leaf has been 

 fully dealt with by Farsky (pp. 109-1 10) in the case of P. conformis 

 mining beet leaves and what is said there holds good for the larvae 

 of P. hyoscyami in belladonna leaves. Reaumur has also given a de- 

 tailed description for the larvae mining in the leaves of Hyosq/anuis 

 niger, and my observations practically agree with theirs. 



The young larva makes its exit from the egg by a small circular 

 aperture at the micropylar end. Operations on the leaf epiderm are 

 immediately commenced with a view to an entrance 'to the underlying 

 mesophyll layers, but at this time its actions are not characterised by 

 excessive energy. The egg-shell collapses when the larva has abandoned 

 it, and a small quantity of frass, the excrement of the tiny maggot 

 as it burrows into the leaf, is left behind. It would appear that an ecdysis 

 occurs on the exit of the embryo from the egg. In all cases where 

 evacuated eggs were examined, a very thin, transparent, delicate 

 membrane was persistently found adhering to the internal walls of the 

 chorion. The whole process of the larval emergence is a progressive 

 one. The larva, by eating its way into the parenchyma, makes a 

 gallery for itself, increases its size, and by bodily extension, rends the 

 egg-shell longitudinally and ventrally. The migration from the egg to 

 the parenchyma is stated by Farsky (p. 109) to occupy a whole day, 

 if the weather conditions are favourable ; if adverse, the operation 

 occupies two to three days, whilst excessive moisture induces abortion. 



Where a large number of eggs are present on one leaf, it is often 

 impossible for all the emerging larvae to find subsistence thereon, and 

 consequently many are sacrificed. On several occasions it was observed 

 that when two or three batches of eggs were deposited on a single leaf, 

 only a few larvae succeeded in attaining maturity. Should a com- 

 paratively long interval elapse between the times of emergence of the 

 larvae from the different egg-bundles, those which hatch earliest stand 



