A. H. Lees 253 



about to hatch, but at the same t ime it is of course possible t hat furl her 

 development might have taken place though this seems unlikely in 

 view of their very bade ward condition. 



The eggs are laid in greatest number at the base of the fruit spurs, 

 often sheltering under the edge of a scale scar ; frequently one side of 

 the spur has more eggs laid on it than the other. I have never observed 

 that the eggs are orientated in a line parallel to the axis of the twig 

 as mentioned by Awati {Ann. Ajip. Biol. Vol. i, Nos. 3 and 4, p. 248). 



As a rule there are but few eggs laid on the vegetative shoots of 

 one year's growth. This occurs only in cases where there is consider- 

 able crowding of eggs on the fruit spurs. 



Description of the Egg. 



By using the caustic soda treatment combined with the use of 

 bleaching powder solution it is possible to distinguish three membranes 

 round the developing larva, which for convenience of description 

 may be called the outer, middle, and inner membranes. 



The outer membrane. This is comparatively thick and has a sculp- 

 tured surface (Fig. 2). It has two processes. One is situated at the 

 pointed end and is solid, being continuous with the thick chitin of 

 the outer membrane. It is hyaline and lacks the irregularity of the 

 sculptured surface which is present on the rest of the outer membrane. 

 It is scarcely possible that it has any influence on the hatching of the 

 egg and appears as if it were pulled out at the time of secretion when 

 the chitin was still soft, in much the same way as a glass rod heated 

 in a flame and pulled forcibly apart leaves a tail of glass (Fig. 2). 



The other process is hollow and is inserted through the back into 

 the cortex of the twig where it ends blindly (Figs. 1 and 3). 



There is a certain amount of disturbance in the cortex as the cells 

 immediately round the process are darker in colour as if cork had 

 been formed as the result of irritation. 



This process certainly serves to anchor the egg and it is possible 

 that by its penetration into the tissues some kind of physiological 

 reaction is caused between the egg and the tree. Of what nature this 

 reaction is it would be impossible to say with any certainty. 



It is at any rate certain that eggs situated on early leafing trees 

 hatch correspondingly earlier than those on late leafing trees. Earlier 

 hatching is therefore associated with earlier rise of sap in the tree. 

 It would therefore appear not impossible that the sudden increase of 



