(>4 HULLETIN OF THK HUKKAir OF FISHERIES. 



Tiiis l<,t of Hshcs, ill salt water, likewise showed a hiolier mortality than 

 those in expoi-iiiieiit Is. thoueji h.Te other causes prolmblv coiiiplicaled the 

 results. 



ACCI.IMATIZATION. 



experiments are, in nature, oiten 

 ieiit he accustomed to it in the 

 lahorator\ hv a comjiarat iv(>l\ rapid process of ac<dimatization. 



:.rj>rnuu,d Jl. 



Woods Hole, AiiM-ust and Septemhei'. Ilt(i4. Twenty-five s(dected si)ecimen> 

 of F. heterocJittis transterivd from salt to fresh water throu.yli hourly steps ol' 

 about 0.(101 in sjiecitic e-r:i\ity." First -2, tishes died 6 days after reachinii' fresh 

 water; -io per cent (10 tishes) died within first 11 days; oidy 2 more died within 

 the following lit days, wIkui the exj)criinent was di.scontinued. 

 It is evident that the harmful elfects of the change to fre.sh water have not heen 

 prevented, though comparison with jireceding experiments suggests tinit they haxc 

 hcic heen diminished. 

 Krj,.rh„a,fJJ. 



Woods Hole, August and September, l!)Oi. Twenty-six /•'. LiaoA'dH.'i 



transferred from salt to fresh water through steps of O.oOl per day.* First 



tish died 6 days after reaching fresh water; 1 more dead and another sick on 



the following daj\ when the experiment had to ))e discontinued. 



It is to be noted that no deaths occurred during the 20 days occupii-d by the 



transfer and that all of the tish were healthy at the time of entering fresh water. 



Taken by itself this experiinent would 



others it is significant. 



If complete a.vlimatization t( 

 of /: h,f, r,,ri;tHs. it is not surprl: 

 Krj.riu.nfJJ. 



Woods Hole. August. 1!»04. 'i'wenty-four large selected /-". i,nij,ii:.s trans- 

 ferred to fresli water tlirougli a series of hourly steps of o.OOl in si>ecitic 

 gravity. (See footnote tuider experiment -J.-!.) First ^ tishes died within li 

 days after reaching fresh watei-; ."i(» [ler cent died within :> days: last one died 

 in S days. 

 ( "omparison with experiments 1 to ."i shows that the period of resistance was 

 somewhat prolonged hy e\en this brief period of acclimatization. 'I"he same phe 

 nomenoii is even better illustrated bv the next experiment. 



'■:■'■/"'■! f.^',. 



Woods Hole, August and September. IIMJI. Same as last, except that daily 

 steps of 0.001 (approxiiiiat<dy) were substituted for hourly ones. Fishes fed 

 throughout. First 2 died 4 days after reaching fresh water; last fish lived i» 

 days (then disappeared). 



" 'I'lu'sf fislu's remained througli one ni.u'hl. Imw ever, nboul nndwiiy in tlie scale. 



''Tlieiii-tiiHl reiuling of the snliuomeler iit 20" C. was liere used, no eorrection being made tor temperature. Ilcnee llie 

 last step was mueli greater than the preeeding ones, being in reality from specific gravity 1.003 to 1, instead of from l.tiul. 



