F, R. Petherbridge and M. A. Husain 187 



Position of eggs. 



The eggs laid in the laboratory were carefully compared with those 

 dissected out of the twigs brought from Walton, and their identity 

 confirmed by comparison mth the eggs dissected out of a female. In all 

 cases the eggs were laid in the present year's soft stem, in many cases 

 very near the apex and in some cases at the thickened bases of the twigs. 

 They were laid indiscriminately in lenticels or in slits made for the pur- 

 pose in other parts of the stem, preference, however, was given to a 

 wound that had become soft, as shown by the presence of a number of 

 eggs in such situations (PI. JX, fig. 3). They were usually laid singly, but 

 in some cases more than one egg was found at the same level both in 

 lenticels and wounds. In the latter situation the number may increase 

 to five or six. 



After a little practice the position of an egg can be easily detected 

 either as a small brown spot or a little slit in the stem, and under magnifi- 

 cation one can easily see the brownish cap of the egg with its whitish rim 

 (see PI. IX, fig. 2). Only a small portion of the cap if any is above the surface 

 of the stem. The long hairs of the stem, to a large extent, conceal the 

 position of the egg which is often made more obscure by the hairs sticking 

 together on account of the exudation of sap from the wound made in the 

 stem, and by the liquid from the body of the female. After a few months 

 the growth of green algae and particles of dust make it impossible to 

 detect an egg by an external examination of a shoot. But if the bark is 

 peeled off carefully the eggs may be detected on the inner side as they 

 usually come off with it. There are no processes extending out from the 

 egg cap. 



Direction of the egg in (he stem. 



The eggs are laid with their long axes more or less radial to the stem 

 and often penetrate the xylem and in young stems reach the pith. Some- 

 times they are more tangential and lie wholly in the bark, this is par- 

 ticularly the case when a number of eggs are laid at the same level with 

 their caps close to each other on the surface. They lie somewhat obliquely 

 with their concave side facing the apices of the twigs and the blunt end 

 situated in front of the cap (see PI. IX, fig. 1 ). Only in one case was an egg 

 found with its convex side towards the apex of the twig (Fig. 3). The 

 greatest diameter of the egg cap is in line with the long axis of the 

 shoot and only in one case when the egg was laid in the scars of the 

 previous year's bud scales was the long axis of the egg cap at right angles 

 to the long axis of the stem. This can be explained on simple mechanical 



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