No. 382.] REVIEWS OF RECENT LITERATURE. 791 
bottom water at a depth of 25 meters. The bottom ooze of the lakes 
is declared to be arena: devoid of life. 
The second paper! is issued by the Balaton Lake Commission of 
the Hungarian Geographical Society, as Part I of a volume dealing 
with the biology of this body of water, a lake containing 650 square 
kilometers, but having an average depth of only 3 meters and a 
maximum of 10. The presence of vegetation, the warm shoal water, 
and the variety of conditions offered in so large a body of water 
favor the occurrence of an extended and varied fauna. It is there- 
fore not surprising that the zoological inventory includes 597 species 
reported by the specialists who have dealt with the various groups. 
The introductory chapter by Dr. Entz contains a description of 
Daday’s ingenious closable trap for bottom collections and an extended 
comparison of the pelagic fauna of the Balaton with that of other 
bodies of water which have been similarly explored. Owing to the 
fragmentary character of the data, precise comparisons are not pos- 
sible, though in a general way it may be said that the organisms 
of the plankton are, as a rule, cosmopolitan in their distribution. 
Attention is called to the invasion of the littoral region by the 
plankton organisms and the depth of 1.5 meters is stated to be the 
limit of the purely plankton-inhabited area of Lake Balaton. That 
this limit cannot be generally applied must be evident. The reviewer 
has often found a typical plankton in water much less than a meter 
in depth. The character and extent of the littoral fauna, and espe- 
cially of the flora, the distance from shore, and a host of environ- 
mental conditions come in to establish, obliterate, or modify the 
boundary lines of the limnetic and littoral areas in most bodies of 
fresh water. Aquatic vegetation is said to hinder the development 
of the plankton, and the author maintains the diurnal migration of 
the plankton organisms, — to the surface at night and to the deeper 
waters during the day. No data upon this subject are given, and it 
may be well in this connection to recall the results of Professor 
Birge’s careful quantitative work ? upon the movements of the Crustacea 
in Lake Mendota. In this body of water the diurnal migration, 
occasioned by the light, is confined to the upper meter or possibly 
two meters. 
1 Die Fauna des Balatonsees, von Dr. K. Brancsik, Dr. E. v. Daday, R. Francé, 
Dr. A. Lovassy, L. v. Méhely, Dr. S. v. Ratz, Dr. K. Szigethy, und Dr. E. Vangel, 
— thers Leitung von Dr. G. Entz. Wien, 1897. xxxix + 279pp. 158 illustrations. 
Birge, E. A. Plankton Studies on Lake Mendota. II, The Crustacea of the 
ata July, 1894 — December, 1896. Trans. Wisc. Acad. Sci., Arts, and Letters, 
vol. xi (1897), pp. 274-448. 
