Si 



cusses the causes which have contributed to the lively interest 

 now being taken in " Seenkunde." He considers that there have 

 been three principal factors at work. In the first place there has 

 been a general deepening of the studies connected with lakes, 

 owing largely to the influence of the rise and progress of Oceano- 

 graphy. Secondly, the individuality of lakes, the fact that every 

 lake is a microcosmos in itself, has had a considerable influence, 

 for it is evidently easier to get a true notion of the interactions of 

 the various forces of nature in a lake than in the sea or in any 

 particular district on dry land. The third factor has been the 

 opening up of the depths of the lakes to investigation by the in- 

 vention of all kinds of ingenious appliances, which has had all 

 the attraction of the discovery of an entirely new province. 



The author then proceeds to a consideration of the lake-basin, 

 dealing with its origin, its gradual alteration in form, the regions 

 into which it is di\ided, and a number of closely related topics. This 

 forms the first of the two parts into which the book is divided. 



The second part is concerned with the water of the lake, and 

 the questions dealt with are very varied and important. For 

 instance under the head of what may be called Hydromechanics, 

 we have the pressure of the water, the alterations in level of the 

 surface, the waves, currents, and so forth. An interesting account 

 is given in this connection of the peculiar oscillations of level 

 occurring in Lake Geneva, and some other lakes, known as 

 " seiches." These remarkable movements, which apparently 

 affect the whole body of water, are now known to be due to 

 differences in the atmospheric pressure over different parts of the 

 lake. The chemistry of the water, together with its thermal and 

 optical peculiarities are next passed in review, and lastly there is 

 a long chapter (80 pp.) on the biology of lakes. The last-named 

 subject is necessarily, to us, the most important, and it is gratify- 

 ing to see that the author has devoted so much space to it. Even 

 as it is he has, of course, only been able to treat the subject in a 

 general way, but the points dealt with, such as the characteristics 

 of the littoral, abyssal and pelagic regions, the origin of lake 

 faunas, the physiology of lacustrine organisms, the circulation of 

 organic material in a lake, etc., are full of significance and should 

 be carefully digested by all who desire to obtain a broad view of 

 the life in a lake. D. J. S. 



Journ. Qv.ekett Microscopical Club, Ser. 2, Vol. VIII., Ko. 48, April 1901. 



