188 
SUMMARY OP CURRENT RESEARCHES RELATING TO 
bito firmly, and its unusually fierce and courageous disposition, which 
has undoubtedly been developed as tho result of successfully withstand- 
ing the attacks of birds. The life-history is given of Orgyia antiqua , 
and there are notes on the early stages of 0. leucostigma, and on the 
transformations of 0. cana. There are notes on a number of other 
species. 
Colours of Lepidopterous Larvae.* — Prof. E. B. Poulton supplies 
tho experimental proof that the colours of certain Lepidopterous larvae 
are largely due to modified plant pigments derived from food. To do this 
he selected a species ( Tryphaena pronuba) the larva of which normally 
eats green leaves, and fed it from the egg with parts of the plant from 
which all colouring-matter is absent. The fact that brown pigments 
may be due to modified plant-pigments is a discovery, but it is not to 
be supposed that in many cases the brown colour is not proper to the 
larvae. 
Although Prof. Poulton’s experiments were successful in establishing 
the conclusion they were intended to test, they point, as he shows, rather 
to the beginning of an investigation than to its end. It is now known 
that certain larval colours are dependent on the existence of modified 
plant-pigments, and this naturally leads to an inquiry into the nature 
and causes of the processes by which chlorophyll and etiolin are, in the 
animal body, converted into a comparatively stable brown or green 
substance, which is far removed from its original position in the diges- 
tive tract, and situated so as to form an important element in the effective 
colouring of the individual. 
Sexes of Larvae of Smerinthus populi.j — Prof. E. B. Poulton has 
made an investigation with the sexes of larvae emerging from the suc- 
cessively laid eggs of Smerinthus populi. He was struck with the com- 
parative rarity of death from internal causes, and is strongly impressed 
with the overwhelming importance of the struggle with highly organized 
enemies in determining the vast amount of destruction which occurs in 
the natural state. The period of development within the egg appears to 
be extremely uniform. The total number of eggs laid by one female 
were 193, from which 68 female and 59 male pupae were obtained. The 
results afford no support to the opinion that the sex of Insects can be 
determined by external conditions during larval life ; it may, however, 
be admitted that the larger female larvae require more food, chiefly to 
prepare for the amount of material to be stored up in the ova. It would 
not, therefore, be surprising if, with a minimum of food, the female 
larvae were starved before the males, but the consequent emergence of a 
number of males would in no way support the view that a scanty diet 
“ determines ” this sex. Prof. Poulton suggests that some writers on 
this subject have mistaken favouring for determining conditions. 
Reproductive Organs of Noctua pronuba.J — Dr. A. B. Griffiths 
gives a short account, which is purely descriptive, of the reproductive 
organs of this moth ; it would appear that this is the first account of the 
organs of generation in the genus Noctua [sic]. 
* Proc. Roy. Soc. Lond., liv. (1894) pp. 417-30 (2 pis.). See this Journal, 1893, 
p. 734. f Trans. Entomol. Soc. London, 1893, pp. 451-6. 
% Proc. Roy. So?. Edinb., xx. (1893) pp. 94-102 (l pi.). 
