REVIEWS OF RECENT LITERATURE. 605 
The work is clearly written, and the author frequently reduces his 
statements to a mathematical form. The book will be useful to 
teachers. 
The Removal from the Water of Nitrogenous Matter Excreted 
by Marine Animals has been investigated by Mr. H. M. Vermon, at 
the Naples Station, by chemical, physiological, and bacteriological 
methods. Green seaweeds in aquaria remove the free, but increase 
the albuminoid, ammonia, and favorably affect the growth of sea- 
urchin larvae. Neither form of ammonia is decreased by the red 
seaweeds, and larve do not thrive in the water except in direct con- 
tact with a small quantity of the weed. Sand with no vegetable 
matter had no purifying power, but when clogged with diatoms and 
algae, it removed as high as 96 per cent of the free, and 51 per cent 
of the albuminoid, ammonia. Bacteria are important agents in the 
purifying process, especially in the removal of the free ammonia. 
The bacterial slime lining the aquarium pipes materially purifies the 
water. Purification is greatest at the maximum rate of filtration, 
though the number of bacteria is increased considerably by the use 
of the clogged sand-filter. The removal of the ammonia favors the 
development of the larve. CAK 
ANTHROPOLOGY. 
Physical Qualities of the Children of Prague.'— Dr. Matiegka, 
one of the foremost Czechish anthropologists, has contributed largely 
to the knowledge of Bohemian craniology and other subjects. The 
present work is a contribution to the study of school children of 
the capital of Bohemia. It has been preceded by studies “On the 
Influences which Act on the Weight and Length of the New-Born 
Children in Bohemia,” ? “ On the Period of Puberty among Bohemian 
Girls,” * etc., by the same author. The work at hand is full of inter- 
esting details and comparisons, and well deserves a translation into 
the English language. 
The children included in the examinations range from 51⁄4 to 14 
1 Matiegka, Jindrich. The Growth, Evolution, Physical Qualities, and the 
Hygienic Conditions of the Children of Prague, 7yans. Bohem. Acad. of Sci. and 
Art, Ann. vi, Cl. ii, No. 17, pp. 1-78, with RS Prague, 1898. 
2 Journ. of the Bohem. Phys. (1894), P. 24 
8 Bull. of the Bohem. Assoc. of Sct. Hey Xv. 
