THE RESPIRATION OF AN INLAND LAKE 



BY EDWAKD A. BII!(JE. 

 Secretary of the Commissioners of Fisheries, Wisconsin 



All inland lake lias orton been f()ni]iai\'(l to a livin>j- hcini;-. 

 and this has ahvavs sccnu'd to nic oiif of the liappicst of tli ■ at- 

 tempts to find n'scnililaiiecs hctwcen animate and inaniinatv 

 objects. I'nlike many sneh (•omi)aris()ns. whieh tnrn on a sinsj'ie 

 point of n'semhlanee and whose fitness disap])ea]-s as soon as 

 the ohjeets are viewed from a different position, the a])propriate- 

 ness of this increases rather than diminishes as our knowled,u'e 

 both of lakes and of liviiio- beiiiiis is enlaru-e(L 



The lake, like the oroanism, has its birth and its periods of 

 growth, maturity, old age, and deatli ; and this fact is an obvious 

 one, for of all the larger features of the landscape, the lake is the 

 youngest and the most temporary. Its birth lies in the recent 

 ])ast and in no very long s])ace of lime ifs existence must come 

 to an end.' In any lake district, lakes may be found in all 

 stages of maturity and decay, and many dead lakes will be sei'ii, 

 — places where lakes once existed which are now extinct. Lakes 

 show not only the cycle of individual existence, Init also thi' 

 rhythm of seasonal activity. 'Vhv acti\'ity of the lake in summer, 

 liotli physit-al and \ital, contrasts sharply with its torpi<]itv in 

 winter. And the lake resemliles the organism not only in its 

 annual recurrence of activity. The comparison may be pushed 

 further and extended to the minor fluctuations of the vigor of 

 vital manifestations which characterize lake and organism alike. 



In all these points, and in many others, the lake resembles 

 a living being; but in no resjiect does it resemble an organism 

 more closely than in the topic on which I am going to speak to 

 you, namely, its rt's])iration. In this coni])arison. the resem- 

 blance is rather in processes and operations than in foi'iii. The 

 lake is morphologically a very simple creature, resembling 

 rather a gigantic amoeba than a more highly organized being. 

 Perhaps it would be better to compare the lake, for the })iir))ose 

 of this subject, not with the organism as a whole, but with the 

 special respiratory substance of the animal — the blood. 



Like the blood of the higher animals, the lake consists of 



