470 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
60 grammes. In fact the author cannot blame them for any direct 
damage, but, none the less, they make a house uninhabitable and life a 
burden. The author has much that is interesting to relate in regard to 
these pests, why they are called after Pharaoh, that they eat everything 
edible except butter, that they do not (as often reported) destroy furni- 
ture, and many other items of information, but he refrains from noting 
how they may be got rid of, which to many would be the first and last 
question. 
Change of Diet in a Beetle.* — Dr. J. Ritzema Bos notes a case in 
which Harpalus ruficornis F., habitually an insectivorous insect, had 
taken to a diet of ripe strawberries. On another occasion they visited 
in the evenings the beds of the country folk and bit the sleepers 
virulently. 
Reducing Division in Spermatogenesis of Gryllotalpa.j — Dr. O. 
vom Rath finds that up to the last spermatogenetic division but one 
the number of chromosomata is twelve, and that the mitoses are like 
those of the body-cells. But before the last division but one twenty-four 
chromosomata are seen in the mother-sperm-cell arranged in six groups 
of four. These are reduced by the second last division to the typical 
number (12), and by the last division to six. Four spermatozoa are 
formed from the mother-sperm-cell, and each contains a chromosoma 
from each of the six groups. 
A Diluvial Cockroach.f — Dr. E. Schaff describes as Perijplaneta 
fossilis the remains of a cockroach found by Dr. 0. Weber in an inter- 
glacial peat-bed in Schleswig-Holstein. The remains are exceedingly 
like parts of a female Asiatic cockroach. Now, if Dr. Weber be right in 
asserting that the insect could not have penetrated at a recent date into 
the peat-bed, two possible interpretations of its occurrence remain. 
Either the records which state that P. orientalis came to Europe about 
200 years ago are wrong, or the insect lived in Europe in diluvial times, 
and afterwards died out. 
Halobatidae of Plankton Expedition^ — Dr. F. Dahl, after a short 
account of the typical structure of a Halobatid, has a few notes on the 
apparent small number of specimens and species collected in the Atlantic 
in 1889 during the now well-known “ Plankton Expedition.” Questions 
that remain to be answered regarding them are, among others, On what 
do they live ? do pelagic fish live on them ? how do the limbs act ? 
B. Myriopoda. 
Eye of Scutigera coleoptrata.|| — Dr. T. Adensamer shows that 
though the eye of this Millipede has the external appearance of a true 
facetted eye, it presents essential differences from the typical form. The 
cornea is the product of two cells ; the refractive body which lies below 
it, though it has the same functions as the crystalline cone of facetted 
eyes, has, as Grenacher has shown, a different structure ; it is made up 
* Biol. Centralbl., xiii. (1893) pp. 255-6. 
f Ber. Nat. Gesell. Freiburg i. B., vi. (1891) pp. 62-4, 
% Zool. Anzeig., xvi. (1893) pp. 17-9. 
§ Ergebnisse der . . . Plankton-Exp. in 1889, Bd. ii. G. a. (1893) 9 pp. (8 figs.). 
|| SB. Zool. Bot. Ges. Wien, xliii. (1893) pp. 8 and 9. 
