ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
169 
tory products of tlie animal utilized in ornament is emphasized by the 
observation that the yellow Pierids on emergence from the chrysalis are 
apt to void from the rectum a quantity of uric acid, coloured by a yellow 
substance, which exactly resembles the pigment of the wing. 
Social Insects and Evolution.* — Prof. C. Y. Riley uses these insects 
as a basis for a discussion of the question whether acquired characters 
are transmitted. He believes that the variations in social insects have 
been guided by natural selection among colonies, but that there has also 
been social selection among individuals. He believes, moreover, that both 
the colony selection and the social selection have notjbeen only along lines 
that were and are useful to the species, but along lines of secondary 
utility and even along lines which are purely fortuitous, and still most 
variable and unfixed. He calls attention to the significant fact that just 
as in Man, among Mammalia, the higher intellectual development and 
social organization are found correlated with the longest period of 
dependent infancy. We are justified in concluding that this dependent 
infancy is in social insects as much as in Man the prime cause of the 
higher organization and division of labour so characteristic of them. 
A Fig-eating Caterpillar.^ — M. Decaux has a note on the caterpillar 
of Simaethis nemorana Curtis, or Tortrix nemorana Hubner, or Asopia 
incisalis Treits, or Xylopoda nemorana Duponchel, which is not un- 
common in the Mediterranean region, and has recently shown itself 
very destructive of the leaves and fruits of figs in the district of Puget- 
Theniers. 
Production of Males and Females in Meliponites.j; — M. J. Perez 
has been able to study the internal economy of the colonies of these 
exotic bees, and finds that there is no essential difference from what 
happens with the French domestic bee. On the other hand, Trigona 
clavipes was observed for several weeks, and found to contain a large 
number of males but not a single female. He has kept a hive of a small 
Trigona from Uruguay under observation for nearly three years, and 
found that it gave rise to a queen in the second year, and virtually 
several queens in the third year, but never to a single male. The pre- 
mature death of the queen stopped the observation and left it undecided 
whether she would have continued throughout the whole of her life to 
produce nothing but females, or if she would not have given birth later 
to some males. In any case the non-simultaneous production of indi- 
viduals of the two sexes in one and the same colony of certain species of 
Meliponites , shows the necessity for cross-fertilization, the advantages of 
which are well known to naturalists. 
Nests of Vespa crabro.§ — M. C. Janet has studied in detail the 
development of the nests of this wasp. He has directed particular care 
to the order of appearance of the first cavities, and has discovered a 
special symmetry to which he calls attention. The first envelope is 
constructed entirely by the mother and remains intact until the appear- 
ance of the first workers. These construct fresh and larger envelopes, 
and then demolish the primitive envelope, which has become insufficient. 
* Rep. Brit. Assoc., 1894, pp. 689-91. 
t Coinptes Rendus, cxix. (1894) pp. 695-6. $ Op. cit., cxx. (1895) pp. 278-5. 
§ Op. cit., cxix. (1894) pp. 1282-5 (8 figs.). 
