MATURATION OF UNFERTILISED EGG IN TENTHREDINID. 560 
ege-laying of the other species in detail, but in C. varus 
and H. rufa the eggs are also arranged with the anterior 
end towards the free end of the leaf. In N. pavidus and 
lacteus the eggs are laid in groups on the lower side of the 
leaf, and in P. luteolum are embedded between the laminz. 
In obtaining the eggs of different ages, the time was noted 
as nearly as possible when any row of eggs was laid, and it 
was then preserved at the desired time. In this way a large 
series of eggs of all ages up to about four hours was preserved, 
and a smaller number of the later stages. The rate of 
development varies considerably with the temperature. 
In most cases a row of eggs was preserved and embedded 
entire, and the eggs cut one after another still attached to 
the leaf, since by this method it was possible to get more 
accurate orientation. Various methods of preserving. were 
tried, including absolute alcohol and acetic acid, Flemming’s 
solution, and other osmic mixtures; but much the best results 
were obtained by Petrunkewitsch’s modification of Gilson’s 
solution (water 300 c.c., absolute alcohol 200 c.c., glac. acetic 
acid 90 c.c., nitric acid pure 10 c.c., sublimate to saturation). 
Some difficulty was experienced in getting paraffin to 
penetrate the eggs preserved in this mixture, and it was 
ultimately found that the best method was to put the eggs 
from absolute alcohol into cedar oil, where they were left for 
a considerable time, and thence transferred to xylol and 
through paraffin dissolved in xylol into pure paraffin. Hven 
then the embedding was frequently defective, especially in 
C. varus, of which a large amount of material was destroyed 
in cutting the sections. 
A number of stains were tried, but the only one that gave 
satisfactory results was Heidenhain’s iron hematoxylin. 
This has the disadvantage that it stains the yolk granules more 
deeply than anything else, but when the position of the 
nuclei in the egg is known they can be found in most cases 
with no great difficulty. 
vou. 49, PART 4,—NEW SERIES. 42 
