PUTREFACTION' IN THE COMMONER FOOD FISH 

 TABLE II. 



101 



Growtli was now allowed to proceed at the room temperature .,of the laboratory 

 which raniged between sixteen and twenty degrees Centigrade. Observations on the 

 rate of growth of the organisms on the media as judged by the rate of growth of the 

 individual colonies were ntade every twenty-four hours. 



For practical purposes we recorded our gi'owths in three categories: — 



1. Rapid growth. 



2. Medium growth. 



3. Slow growth. 



Fig. 1 on plate shoAvs by way of illustration organisms Alpha and Beta plated in 

 sardine agar after forty-eight hours* growth. Fig. 2 shows organisms Alpha and Beta 

 plated in eel pout agar after forty-eight hours' growth. 



It will be plainly seen that sardine agar is the much more suitable culture medium 

 for the early and rapid growth of these organisms. 



After forty-eight hours our results for the complete sets were as follows: — 



1. Rapid growth — Sardine and cod. 



2. Medium growth — Flounder, hake and skate. 



3. Slow growth — Eel pout, haddock and pollock. 



After five days a curious change occurred in the rate of growth. A number of 

 plates in which the colonies had at first grown slowly caught up to a-nd in some cases 

 grew more rapidly than others that had shown the greatest growth at the beginning, 

 so that the plates could now be classified as follows : — 



1. Rapid growth — Sardine and eel pout. 



2. Medium growth — ^Haddock, cod and hake. 



3. Slow growth — Skate, pollock and flounder. 



These experiments were carried out in duplicate with practically identical results. 



The explanations which suggest themselves for this phenomenon of change in 

 the rate of growth are, (1) that organisms which grow slowly at first on a given 

 medium may by adapting themselves to the medium later grow more abundantly; (2) 

 that the media which are more suitable for rapid growth early after seeding may 

 present their maximum growth quickly, and by the rapid apfuniulaion of deleterious 

 waste products before they can diffuse into the surroundinj^* medium, somewhat retard 

 the rate of growth. 



Whatever the explanation, it seems quite reasonable to assume that the media 

 giving the earliest and most abundant growth of the colonies represent the fish which 

 will be the first to show putrefactive changes, and that those which give the slowest 



