1S6 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Pigmentation in eales of Lepidoptera and Coleoptera.* * * § — Dr. F. 
Urech gives a detailed discussion of this subject, to which he has 
previously made numerous contribution s.f In these he gave evidence 
in support of the conclusions that the simplest pigments are greenish- 
yellow to yellow, and that, with increasing molecular weight in the 
pigments, orange, red, violet, blue, and green may successively arise, and 
that sometimes there is in the ontogenetic succession of colour a re- 
capitulation of the phylogenetic progress. Another important general 
conclusion, to which Urech has contributed, is this, — that the pigments 
of the scales in Lepidoptera belong to the uric acid group and to related 
groups, including the “ nuclear-bases ” (xanthin, hypoxanthin, adenin, 
guanin), which are so-called because they are the spontaneous decompo- 
sition-products of nuclein along with albumen and phosphoric acid. 
Individually, these nuclein-bases are colourless, but their mutual actions 
produce green and violet and otherwise coloured by-products. Perhaps 
the nuclein-bases arise from leucocytes which part with their pigment to 
epithelial cells. 
After explaining his chemical and physical methods, Dr. Urech 
gives a summary of his results as to the behaviour of the pigments in 
relation to various reagents. These results are stated in over two 
dozen pages of tables. The most general result is that from white to 
yellow, and onwards through red and brown, the pigments are less and 
less soluble in water, until solution in water becomes impossible, as is 
the case with blackish pigments which are usually soluble only in nitric 
acid. 
Androconia of Lepidoptera.! — Mr. M. B. Thomas discusses the 
so-called scent-scales or hairs of male Lepidoptera. He finds them to 
be the outlet of certain glands in the tissue of the wing beneath the 
androconia-bearing surfaces. When the surface of th« wing is covered 
with a large number of papillae, from the end of which the scent-scales 
project, the latter are quite small, and there is but one to each papilla ; 
this gives the scale the appearance of a small rod placed in a flask. The 
material elaborated by the glands and distributed on the surface of the 
wing by the androconia gives to many Lepidoptera their characteristic 
odour. 
Development of Compound Eye of Vanessa. § — Mr. H. Johansen 
denies that the fii st step in the formation of the eye is, as Patten states 
for Vespa, an invagination. The cells of the epidermis unite to form 
ommatidia soon after the eyes of the larva are detached from the 
epidermis. Of the numerous leucocytes which owe their origin to the 
dissolution of the organs of the larva, thirteen take part in forming an 
ommatidium ; the cells which carry Claparede’s “ nuclei of Semper ” may, 
the author suggests, be called Semper’s cells. There appears to be 
sufficient evidence that the facetted eye of tracheate Arthropods should 
be considered as, phylogenetically, an assemblage of simple eyes. The 
* Zeitschr. f. wiss. Zool., lvii. (1893) pp. 306-84. 
t Zool. Anzeig., xv. (1892) pp. 284-90, 293-306. 
X Amer. Natural., xxvii. (1893) pp. 1018-21 (1 pi.). 
§ Congres Internal, de Zoologie, ii.. part 2 (,1893) pp. 124-6. 
