29 



(lied (311 the second day, however, without having Laid any eggs. 

 On dissection the nterns was found to he tilled with a large ninn- 

 lier of eggs. Some of these were examined, and all stages of de- 

 xeloinnent were fonnd, some ap])areiitly ready to hatch. Exam- 

 ination was made hy placing a number of eggs on a glass slip and 

 ap})lying pressure with the point of a knife blade, when the 

 .shells of the eggs would burst with an audible snap and allow 

 the embryos to emerge, many of them without injury. Some 

 of these were still retained in the vitelline membrane, while 

 others were entirely free from it and were to be seen crawling 

 about, which shoAvs that they are fully developed, ready to 

 hatch, before the eggs ai'e laid. This accords with the observa- 

 tions of Townsend and Sasaki. ^lany of tliose still enclosed 

 in the vitelline membrane, were seen to l)e active, wriggling 

 about, revolving and even doubling u]), as fully developed as 

 those which had escajx'*! fi-om the vitelline membrane. 



Some of the eggs from this same female were retained in a 

 dry condition in a vial. They were examined from time to 

 time, and it was found that at the eii<l of four weeks, there 

 were some of them with living eud)ryos; showing that they 

 undoubtedly may remain alive on tlie leaves of plants for some 

 little time, if not immediately eaten by caterpillars. 



As regards the hatching of tachinid eggs after being eaten 

 by caterpillars, no satisfactory explanation has yet been given. 

 The shell of the egg, is so hard that it seems unlikely that it 

 could be sufhciently affected by the digestive juices of the 

 caterpillar, quickly enough to allow the maggot to escape from 

 the egg, and also have time enough to pass thru the wall of the 

 alimentary canal before it would be carried along and be ex- 

 pelled with the frass of the caterpillar — this latter being a 

 rather rapid process in a normally feeding caterpillar. 



In my earlier notes, above, I have said that the eggs are so 

 small as to escape being injured by the jaws of the caterpil- 

 lars in biting otf bits of leaf. I quote the following from 

 Townsend on page 109 of the bulletin above referred to: 

 "Furthermore, the chitinization strengthens the egg and thus 

 lessens the chance of injury to it while being swallowed. Still 

 further, we have found that the chorion of all these eggs pos- 

 sesses a minute raised reticulation, which we consider is in- 



