276 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Arthropoda. 
a. Insecta. 
Parabiosis among Ants.* — Dr. Auguste Forel applies this term to 
a new form of association which he discovered in Colombia between a 
species of Dolichoderus and one of Cr emastog aster. The two lived in one 
nest, which in the first observed case was a large conquered termites’ 
nest, but the life of the two species was perfectly distinct. The foraging 
parties of the two species set off from the nest in company, and were 
often seen running side by side over trees and the ground. Ultimately 
they separated, to seek each their special food. The galleries of the 
nest were exactly as left by the termites, and were each occupied by 
one of the species only without any intermixture of the other ; but the 
galleries of the two species were in free communication. Such a con- 
dition of affairs has not hitherto been described for ants. The paper 
concludes with a list of the kinds of associations found among ants, with 
examples and definitions. 
Embryonic Membranes of Insects.f — Dr. Arthur Willey puts for- 
ward a theory as to the phylogenetic origin of trophoblast and serosa, 
based especially upon his observations on Peripatus novse-britannise. Iu 
this species the embryos possess a trophoblast which, by virtue of its 
close proximity to the uterine mucosa, acts as a mucous membrane. 
The author believes that the oviparous habit of insects is secondary, 
and that the embryos were once enveloped in a trophoblast, which, like 
that of Peripatus novse-britannise, was an absorbent mucous membrane. 
When oviparity was acquired, the trophoblast became converted into 
blastoderm and serosa by substitution. The amniotic cavity, on the 
other hand, was originally a product of invagination, the invagination 
being “ primitively derived from and associated with a ventral flexure 
of the embryo.” 
Japanese Collembola.J — Mr. J. W. Folsom publishes a second 
paper on this subject, in which he describes six new species and one 
new variety. The paper also includes a list of the species at present 
known to inhabit Japan. 
Absorption in the Cockroach.§ — Prof. L. Cuenot publishes an in- 
teresting criticism of Metalnikoff’s results as to the precise area in 
which absorption takes place in the intestine of Blatta orientalis. Prof. 
Cuenot’s earlier researches |] led him to the conclusion, also arrived at 
by others, that the mid-gut is the absorptive area ; but Metalnikofif,ir in 
re-investigating the matter, came to the conclusion that absorption takes 
place only in the terminal part of the intestine. His method was to 
feed the cockroaches on bread soaked in a salt of iron (ferrum oxydatum 
saccharatum), and later treat the intestine with potassium ferrocvauate 
and dilute hydrochloric acid. He found that the Prussian blue reaction 
developed only in the hind-gut, and hence concluded that here only had 
* Bull. Roc. Vaud., xxxiv. (1898) pp. 380-4. 
t Quart. Journ. Micr. Sci., xli. (1899) pp. 589-609 (6 figs.), 
t Proc. Amer. Acad. Sci., xxxiv. (1899) pp. 261-274 (3 pis.). 
§ Arch. Zool. Exp., vi. (1898) pp. 65-9 (2 figs.). 
|| Arch. Biol., xiv. (1895) p. 293. 
<[| Bull. Acad. Sci. St. Petersbourg, iv. (1896) p. 495. 
