Am fried II Fislirrirs Sucich/ ' 2ol 



inli;il)ital)k' foj- lii^ilie)' animals. This fact vxcludes from our 

 lakes a .uood majiy kinds ot' animals which they mi<;ht other- 

 wise su])i)ort. and verv ,urcally limits the (juantity of the hii^iier 

 life whieli tlie lake is ahle to maintain. A hd<e whieh loses its 

 hottom o\y,ii-en. for example, eannot su])i)ort a (ish, as the hd<e 

 ti'out, whieh must I'etij'e to the deeper and eoolei- water diii'ini;- 

 the summei'. To sut'h causes may ])rohahl\' he attrihuted a 

 consideiahle inimher of our Tailures in the i)lantiu,i:- of hsh in 

 our inlaiul hd\-es. l''i-om causes such as thest\ the whole of the 

 lower watei'. contaiiun.u' lialf. or uiore, of the xolume of the lake, 

 nuiy hecome iinijdud)itai)le during the seas(ui wlicu life is most 

 ahuii(hnit: and the (|uantity of life which the lal<e su])])oi-ts nuiy 

 ])v cori-espondingiy limited. 



Still further, since the I'apidity with which the oxygen is 

 exhausted deix'iids on the anu)unt of material which is deposited 

 in the lower water, those lakes whose u])per water contains the 

 gi'catest (piantity of vegetahle life, ami which can thend'ore sup- 

 port the greatest amount of animal lift', use up the oxygen of the 

 lower water most rapidly. It looks, thercd'oi-e. as if we were in 

 a somewhat unfavoral)le situation as regards the ])0ssihilities of 

 higher life in the lower water of iidand lakes. Those lakes 

 whose food su})ply is such that they art' capahle of su])porting 

 large quantities of animal life — 1 may say for our purposes, 

 large jiumhers of fish — are likely from that very fat-t to exhaust 

 the stock (d' oxygen in the lowei' wattT. whicli thus heconies 

 uuiidiahitahle : while those lakes whose Iowht watei' is fully 

 hal)itahle are likely to he so |)(ioi' in organic life that they can 

 su])])oj't o]dy a limited nundier of fish. It may hi' that further 

 study will show that this ri'hition is not so unfa\-oral)le as it now 

 aj)pears, l)ut at ])resent we must face the prohahility that it 

 exists. 



A noteworthy t'xce])tion to this statement should he made in 

 the ca.st' of vei-y deep lakes — lakes two humlred or nioi'e feet in 

 de])th — in which the (piantity of the lower water is so great and 

 the c()US((|u; ii.t iimount of dis^olv:(l oxygen is so considerahle 

 that no ordinary amount of decomposing material can exhaust 

 it or nuUerially I'l'duce it. This is the ease, for example, with 

 (Ireen Lake cy.\] feet in depth) in Wisconsin, ami the same 

 statement would douhtless hold for the dee]) lakes of \ew York 



