of the experiment are plotted in Fig. 19. The heavy lines, N and B, above the zero level express the relative efficiency of Nig and Bum, and indicate the number of balls retrieved by each dog. The light lines, n and b, express the number of times each dog attempted to get the ball. Nig's line of achievement is seen to run much closer to his line of attempt than in the case of Bum. Fatigue is expressed below the zero line, and is derived from the number of times each dog lay down to rest. Nig shows fifteen per cent of Bum's fatigue. Expressed in other words, Bum lies down to rest 67 times to Nig's once.
It is clear that we must advance beyond the usual anatomical standards of comparison into the field of function, if we are to arrive at any definite settlement of physiological questions. Efficiency, ability to do work, must be the ultimate appeal. While nothing is further from my thought than to claim for the foregoing experiments sufficient comprehensiveness to even approximate to a solution of this important problem, still, as stated at the outset, their results may serve to hint at the possibilities of future work. The experiments are still in progress, their continuance being assured for one more year by the Committee of Fifty. It is to be hoped that they can be carried on much longer, to yield, at least, the complete life story of the original four dogs. The
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| Fig. 19.—Chart of Bail Tests. |
present opportunity should also be utilized to study the next generation in a similar way, if there should appear marked signs of degeneration. Results are certain to increase in definiteness and value as the experiment is prolonged out of all proportion to additional cost.
On the side of physiological activity, while a number of other forms should be studied, and experiments need repetition to guard against individual variations, the results obtained—retardation in growth of yeast, and depression of activity in kittens and dogs—cast a suggestive light on the human experiment. The spontaneous desire and the will welling up within a vigorous organism to be and to do something worth the while seems to me the highest thing in life. Hence knowledge concerning physiological conditions which favor elaboration of this quintessence of existence possesses a human value beyond computation or expression,
Helmholtz has said, in describing his methods of work, that
