ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
07 
Functions of White Blood-Corpuscles. * * * § — Herr Hs. Friedenthal 
gives a useful summary of recent work on this subject, and sums up as 
follows. It seems certain that the leucocytes play an important part in 
connection with coagulation (both preventing it and causing it), in 
phagocytosis, and in the secretion of the protective substance known as 
alexine. Their phagocytic activity includes the removal of dust-particles 
from the lungs, of pigment from the epidermis, of necrotic portions, and 
of intrusions. They play an important part in transporting material 
during metamorphosis ; in regeneration they furnish the first material ; 
the blood-plates are in part due to their disruption. Requiring confir- 
mation, however, are the suggestions which have been made as to the 
share of the leucocytes in forming blood-ferments, in absorbing food, and 
in forming red blood-corpuscles. In short, they represent a reserve- 
power in the organism, helping various tissues in various ways to resist 
injurious influences and to respond to special functional demands. 
Melanism in Reptiles and Amphibians.f — Herr Fr. Werner has a 
stringent criticism of Tornier’s J conclusion in regard to melanism in 
reptiles and amphibians. Tornier committed himself to the statement 
that melanism is to be regarded as a reversion to the original colour of 
the species. Werner gives many reasons why this cannot be accepted, 
and discusses in particular the import of the black colour in free- 
living amphibian larvae. If every species with melanism was originally 
black, then the coloration of all these forms must have evolved inde- 
pendently, and all homologies in the coloration of related forms are mere 
analogies. 
Freshwater Fauna.§ — Prof. S. J. Hickson gives an interesting 
statement of the problems connected with the distribution of the fresh- 
water fauna. He recognises three groups (1) the Cosmopolitan 
group, illustrated by Hydra , Spongillct, Astacus, Anodon , Lymnsea; 
(2) the Archaic group, illustrated by Apus, Dipnoi, Limnocodium ; 
(3) the Recent group, illustrated by Cordylophora, Pcdsemonetes, and the 
prawn in the Tropics. 
INVERTEBRATA. 
Mollusca. 
y. Gastropoda. 
Apex of Gastropod Shell. (J — Mr. F. C. Baker has studied the apex 
of the shell in 132 species, which, as he notes, is a small fraction of the 
total of 15,000 or so. There seem to be three main types, with numer- 
ous variations : — (1) whorls numerous, carinated, nucleus prominent ; 
(2) whorls numerous, rounded, smooth, nucleus prominent ; (3) whorls 
few, rounded, nucleus buried in the coil of the second whorl. Great 
changes take place after birth, many of them apparently modifications 
due to environment. It would be interesting if the author could in 
this case bring out the difference between variation and modification. 
* Biol. Centralbl., xvii. (1897) pp. 705-19. f Tom. cit., pp. 376-SI. 
x ‘ Die Kriechthiere Deutsck-Ostafrikas. Beitrage zur Systematik und Desccn- 
deuzlehre,* Berlin, 1897. 
§ Trans. Manchester Micr. Soc., 1896 (1897), pp. 88-99. 
U Ann. New York Acad. Sci., ix. (1897) pp. 685-704 (3 pis.). 
