THE GROWTH OF FISHES. 



By Professor A. G. Huntsman, 



University of Toronto, Biologist to the Biological Board of Canada. 



"Greater production" is the cry of the present day and the 

 imperative need of the hour. In the realm of living things, 

 either plant or animal, this production is virtually synonymous 

 with growth. The desired product is the result of growth, and the 

 problem of growth is, therefore, one of extraordinary interest to us. 

 With the broad lines of this problem we are familiar through our 

 knowledge of the life history of man, if from no other source. 

 The early part of life is the growing period and under suitable 

 conditions, such as with sufficient food of certain kinds, sufficient 

 water and air, a temperature not too extreme, and no unfavorable 

 circumstances of poison or disease, the growth of man proceeds 

 uninterruptedly, but with gradually decreasing intensity, until the 

 period of maturity is reached, when general growth ceases. 



The problem of growth is an enormously complex one and has 

 ever new angles. This is shown by the comparatively recent 

 discovery in certain foods of special substances, to which the name 

 of vitamines has been given, and which have a wonderful effect 

 in accelerating growth. That, from the standpoint of growth, we 

 can improve upon what nature shows us, is demonstrated by the 

 use of the method of forced feeding in poultry and of caponization 

 for cockerels. 



We are greatly handicapped in our study of growth in fishes by 

 their living in the medium of water, to which we have only imper- 

 fect access. It is a comparatively easy matter to watch the 

 growth of plants, and in the case of animals, if they live on land, 

 one can keep them under almost constant observation. But we 

 can see only a short distance into the water, and even that view 

 is interrupted by every breeze, however slight, that agitates the 

 surface. Consequently our knowledge of the growth of fishes has 

 been extremely limited, for until very recent years it was a moot 

 point as to the age attained by the commonest fishes, except for 

 a few that could be kept in restricted bodies of water under more 

 or less artificial conditions. 



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