452 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
and its regular segmentation, while the third begins with the appearance 
of the rudiments of the gnathites, and ends with the formation of the 
anus ; the fourth includes the rest of the intraovular development. 
It should be noted that all of the so-called yolk- cells do not come to 
the surface in the formation of the blastoderm ; much remains behind in 
the yolk. It is quite easy to see distinctly in Chalicodoma that, later on, 
there is neither a migration of yolk-cells into the already formed 
blastoderm or into the meso- or endoderm, or, on the other hand, a return 
of the cells of these layers into the yolk. 
The Poison and Sting of the Bee.* — Dr. G. Carlet finds that in 
Hymenoptera with toothed stings there is in addition to the well-known 
“acid-gland” another with an alkaline secretion which renders the 
poison fatal. In Hymenoptera with smooth stings, which benumb their 
victims without killing them outright, this extra “ alkaline gland ” is 
rudimentary or absent. He describes the piston which makes the sting 
a double syringe, and shows how the cistern of poison feeds the syringe 
in such a way that the secretion does not flow out unless the whole 
apparatus is brought into action. The articulation of the stilets is the 
same in principle as the cabinet-maker’s sliding dovetail. Of the 
detailed parts of the sting, the author claims to have given a more exact 
account than heretofore, of the truth of which Mr. Cheshire can judge. 
The Genus Prosopistoma.j - — M. A. Vayssiere begins a monograph 
on this interesting Ephemerid., which has received such varied treatment 
at the hands of naturalists. Of the European species P. foliaceum, the 
male adult is still undiscovered, while the Madagascar forms (P. varie- 
gatum ) are known only in the “ larval-nymphal ” stage. The young 
forms of the European species live in rapid rivers, such as the Seine 
and Rhone, under stones, in company with small insect larvae. They 
swim rapidly, avoid the light, and probably feed on Protozoa and organic 
debris. Making a sort of sucker of their body, they also adhere firmly 
to the surface of stones. In swimming they use chiefly the three hairy 
bristles at the posterior end, while the head seems to be directive. The 
habits and the frequent moults of the “ larval-nymphal ” forms were 
studied by M. Vayssiere on captive specimens. So far, the author 
describes the tegumentary, muscular, alimentary, and vascular structures, 
but the general results may be reserved until the completion of the 
monograph. 
Anatomy of Thysanura.J — Mr. H. T. Fernald gives an abstract of 
his studies on Thysanuran anatomy. Anurida maritima has been fully 
examined, and in some points Lepisma saccharina. The structure which 
Sommer called the “ Excretionsorgan ” in Macrotoma is present in 
Anurida , and is regarded by the author as the homologue of the fat- body 
of higher insects ; its connection with the hypodermis is only secondary. 
Near the origin of each of the main nerve-trunks there lies a very large 
nucleus, which is more than twice the size of the nuclei of nerve-cells, 
but the author has not been able to ascertain its significance. Tactile 
bristles are scattered over the surface of the body, and are especially 
abundant on the antennas and round the mouth. On the terminal joint 
* Ann. Sci. Nat. (Zool.), ix. (1890) pp. 1-17 (1 pi ). f T. c., pp. 19-64 (1 pi.). 
X John Hopkins Univ. Circ., ix. (1890) pp. 62-3. 
