ACADEMY OF SCONCES.] BIOGRAPHY. 187 



the young American's abilities. The invention of the "Bowditch clock" to mark various periods 

 time was another product of his Leipzig experience. In the Harvard Laboratory a new form 

 of induction apparatus, with the secondary coil turning at various angles to the primary, and 

 permitting in brief compass variation of intensity of the induced current, a new form of plethys- 

 mograph to register changes in the volume of organs, a new apparatus for artificial respiration, a 

 novel animal holder, a cannula for observing the vocal cords, and a special arrangement of 

 unpolarizable electrodes were evidences of his ingenuity. Apparatus, however was always a 

 means to an end and never became a central interest for him. 



Two papers were published on the basis of work done under Ludwig's direction. The first, 

 on peculiarities of the irritability of cardiac muscle, has become a classic in physiological litera- 

 ture. In this contribution are pointed out two fundamental characteristics — the "Treppe, " 

 or step-like increase of contraction, in response to a repetition of uniform stimuli, which is 

 accounted for by the effect of activity itself in causing greater responsiveness in the tissue; 

 and the "all-or-none law," i. e., the contraction of cardiac muscle to a maximal extent, at the 

 moment, independently of the strength of stimulation, or no contraction whatever. The former 

 observation has been proved to be generally true of irritable structures and is at the basis of 

 "warming up" for action; the latter has been extended in recent years to the contraction of the 

 fibers of skeletal muscle and to the passage of impulses along nerve trunks. The second paper 

 was concerned with the interference between accelerator and inhibitor nerves on the heart as 

 influenced by variations of arterial blood pressure. 



Interest in the physiology of cardiac muscle was continued in the laboratory at the Harvard 

 Medical School, and resulted in a demonstration of the incapacity of the apex of the frog's 

 ventricle to show a spontaneous rhythm after being isolated from the base, though normaUy 

 nourished and though remaining irritable to external stimuli. 



Wyman had called attention to the ability of ciliated epithelium to exert a force by no means 

 inconsiderable. This observation Bowditch made the subject of an investigation and by having 

 the ciliated cells move weights up an inclined surface he calculated that in a minute they did 

 an amount of work equal to lifting their own weight 4.25 meters. When he demonstrated 

 this effect in Leipzig at one of his visits to Ludwig it aroused much interest among the group 

 of investigators there. 



Another line of interest developed in the Harvard Laboratory was concerned with the nervous 

 control of blood vessels. As early as 1874, Bowditch and Minot published a paper showing 

 that chloroform has a much more profound effect than ether in depressing vasomotor reflexes. 

 Later Bowditch and Warren undertook an extensive investigation of the influence of different 

 rates and strengths of peripheral stimulation on the contraction and relaxation of blood vessels. 

 This study, which has received much attention, showed that by varying the nature of the 

 stimuli it was possible to produce constriction, or constriction followed by dilation, or dilation 

 alone — rapid stimulation favoring constriction and later dilation. This mode of separating 

 vasoconstrictor and vasodilator effects was extended by means of experiments on degenerated 

 nerves. It was found that whereas immediately after nerve section a given stimulus caused 

 pure constriction, the same stimulus applied to a nerve which had been severed four days pre- 

 viously induced a pure dilation. These results have suggestive values which have not yet 

 been fully appreciated. Similar reversals of effect were reported by Bowditch in relation to 

 etherization. Thus the glottis may be constricted or dilated according to the degree of ether-i 

 ization and the strength of the stimulus applied to the recurrent laryngeal nerve. Likewise in 

 the frog extension of the leg and abduction of the toes, as a result of exciting the sciatic, will 

 give place, under ether, to flexation and abduction. 



With Garland, Bowditch investigated the effect of the respiratory movements on the pul- 

 monary circulation, and came to the conclusion that expansion of the lungs diminishes the size 

 of the pulmonary vessels, and that collapse of the lungs has the opposite effect, the changes 

 being more marked on the venous than on the arterial side. 



The functioning of the nervous system was for a time a central interest in Bowditch's 

 thinking. "What conception can one form of the physical or chemical changes which take 



