bowditch's apparatus. 



305 



Fia. 136.— Dr. H. P. Bowditch's Apparatus for ExperimentB on the Heart 



of the Frog. 



A is the frog's heart, b is a cannula tied into tlie vena cava, and b' one into 

 the aortic bulb. C, & and c" are three glass stopcocks. By c fresh serum is 

 supplied, by c' old serum is let out, and c" allows the communication between 

 the bent tube b c' b' and the manometer m to be opened or shut at will. D is a 

 glass plate, through which the bent tube B c' b' passes, e is a rod ending in a 

 ring into which d is fitted, r is a nut by which the whole apparatus can be 

 moved up and down on the stand a. h is a T-tube. J and j' are two clips to stop 

 the flow of serum from K or k'. k and k' are two fountain-bottles for supplying 

 serum to the heart, k contains pure, and k' poisoned serum, l and l' are bent 

 tubes which convey the serum out of K and k'. m is a small manometer, n is 

 the pen or point which swims on the mercury. The horizontal part is made of 

 glass ; the vertical rod of esparto grass, with a small piece of sealing-wax at its 

 lower end. The tracing may be made with ink, or with a dry point on smoked 

 paper, p is a small weight which hangs by a piece of unspun silk from a bent 

 wire, and keeps the pen resting on the paper, q is the revolving cylinder. E is 

 the clockwork, which is provided with one of Foucault's regulators, s is a table, 

 which can be raised or lowered at pleasure, and fixed at any height by the 

 screw T. V is an india-rubber tube, tlirough which the serum is emptied from X, 

 X is a graduated tube, into which the serum is allowed to pass after it has circu- 

 lated some time. Y is an india-rubber tube, which is generally closed by a clip, 

 but is opened when the apparatus is to be filled, or when we wish to let down 

 the mercury to zero, in order to draw an abscissa, w is a glass vessel, which 

 fits tightly to the under side of D, and protects the heart from external irrita- 

 tion. Into the two holes seen in d tubes may be fitted air-tight, and the heart 

 made to pulsate in an atmosphere of any sort of gas.* 



* This apparatus is made bj Qeisler, Blume's Hof, Berlin. 



Mr. Hawksley, 

 X 



