ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
155 
Arthropoda, 
a. Insecta. 
Parthenogenesis in Lepidoptera.* — Prof. M. Nussbaum gives an 
interesting historical account of what has been previously observed in 
this connection, and a summary of his own experiments on Bornbyx mori, 
Porthesia chrysorhoea , and Liparis dispar. It was only with the first 
named, however, that he succeeded in demonstrating parthenogenetic 
development. Out of 1102 unfertilised ova of the silk-moth, 22 de- 
veloped up to a certain point; while out of 1260 fertilised eggs, 1190 
developed — a contrast of 2 per cent, and 94*5 per cent. The un- 
fertilised ova showed segmentation and a slight blastoderm, but never 
hatched ; while 70-91 per cent, of the fertilised eggs hatched success- 
fully. In most cases unfertilised and fertilised eggs were observed from 
the same mother, and the two sets were kept as far as possible in the 
same conditions, so that the decisive factor is clearly the occurrence or 
non-occurrence of fertilisation. 
Castrated Caterpillars.} - — Herr J. Th. Oudemans has succeeded in 
the difficult operation of castrating caterpillars, and finds that the pro- 
cess has little result either on the extornal appearance or on the habits 
of the adults. 
Mosquitoes and Malaria.}: — SS. B. Grassi, A. Bignami, and G. 
Bastianelli come at present to the following conclusions. 
The Hmmosporidia or Haemamoebinae of malaria pass in a man 
through a chapter of their life-cycle characterised by the long duration 
of the amoeboid phase and the absence of encapsuled stages. How many 
times they may reproduce is undetermined ; but they also give rise to 
forms which remain sterile in man. The last reach the intestine of the 
adult Anopheles claviger Fabr., and develop as typical Sporozoa, form- 
ing an enormous number of sporozoites, which accumulate in the salivary 
glands, and return to man in the process of puncturing. It is claimed 
as demonstrated that the parasites pass directly from man to mosquito, 
and from mosquito to man ; but other species of Diptera besides Anopheles 
claviger may also share in the dissemination, and the question of passage 
from the parent insect to its offspring is left open. 
Development of Head of Hymenoptera.§ — L. G. Seurat describes 
the formation of the imaginal head in a Braconid, Doryctes gallicus, a 
point in regard to which there has been much controversy. The general 
verdict hitherto has been that the head of the imago is formed from the 
head and the first segment of the body of the larva. Seurat’s obser- 
vations show that the head is wholly formed from the head of the larva. 
It is at first invaginate, but by a rotation in the median plane it is 
evaginated, and assumes its final form. 
Wings of Insects || — Messrs. J. H. Comstock and J. G. Needham 
now discuss the venation of Odonata in illustration of the specialisation 
* Arch. Mikr. Anat., liii. (1898) pp. 444-80. 
f Zool. Jahrb., xii. (1898) pp. 71-88 (3 pis., 2 figs.). 
% Atti R. Accad. Lincei (Rend.), viii. (1899) pp. 21-8. Cf. this Journal, ante , 
p. 32. § Comptes Rendus, cxxviii. (1899) pp. 55-6. 
|| Amer. Nat., xxxii. (1898) pp. 903-11 (figs. 60-68). Cf. this Journal, ante, p. 31. 
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