ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
355 
Arthropoda. 
a. Insecta. 
Embryology of Insects.* — Herr N. Cbolodkovsky, answering V. 
Grabor’s criticism of a former paper, maintains his position that the 
supra-cesopliageal ganglion of Blatta germanica developes from three 
pairs of rudiments. He also adheres to his attempt to explain the dif- 
ferent forms of the blastopore in insects. 
Colours and Markings of Vanessa.| — Dr. F. Urech recalls his ob- 
servation of the frequent resemblance between the colour of the urine 
and that of the scales in many butterflies. Since the chlorophyll eaten 
by the caterpillar is voided unchanged, only colourless or white sub- 
stances being digested, the pigments in the scales and Malpighian tubes 
must be either analytic or synthetic products of the food. Like Schaffer, 
Urech finds that the different colours of the scales arise from a uniform 
origin (chromogen), thus the scales are at first dark reddish in Vanessa 
urticse, quite white in V. Io. A list of about thirty species is given, 
showing the (frequently congruent) colours of urine and scales. 
The progress of coloration in ontogeny affords useful aid in deter- 
mining the phylogeny. In the ontogeny of the V. Io pupa the succession 
of colours is white, yellow, red, brown, and black ; the predominant 
colouring of Papilio is bright yellow, of Vanessa yellow to brown-red, 
of Hipparchia brown to blackish, of Apatura dark-brown to black ; but 
this order Papilio, Vanessa, Hipparchia, Apatura seems to be phylo- 
genetic ; thus there is a general correspondence between the ontogenetic 
and the phylogenetic succession of colours. 
Development of Mantis religiosa.J — M. H. Viallanes deals chiefly 
with the development of the central nervous system. He finds that it is 
entirely developed at the expense of a pair of ectodermal thickenings 
which extend from the procephalic lobes to the caudal extremity of the 
embryo. At the cephalic end the primitive ridges are widened and 
segmented into five lobes. The first, second, and third formed the 
so-called protocerebrum ; the fourth the deutocerebrum ; and the fifth 
the tritocerebrum. In the first of these the ectoderm thickens and then 
becomes delaminated into two layers, which soon separate from one 
another. The outer forms the compound eye ; the inner layer the first 
protocerebral lobe. The ear-cells of the latter may well be called the 
gangliogenous-cells, for they indirectly give rise to the ganglionic cells, 
and, as soon as the first ganglionic cells are formed, they undergo 
degeneration. As the cells multiply they produce between them the 
fibrillar substance, which forms the central nodule of the protocerebral 
lobe, and is invested by a ganglionic cortex. The fibrillar centre 
becomes divided into three distinct regions — the internal layer, the 
external chiasma, and the external medullary mass. The ganglionic 
cortex is differentiated to form the internal layer of the ganglionic plate, 
and the different groups of ganglionic cells which send prolongations to 
the external medullary mass. At a relatively late period postretinal 
nerve-fibres are formed between the ganglionic layer and the optic plate, 
* Zool. Anzeig., xiv. (1891) pp. 465-6. f Tom. cit., pp. 466-73. 
J Arm. Sci. Nat., xi. (1891) pp. 283-328 (2 pis.). 
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