744 DB, FRASER ON THE PHYSIOLOGICAL ACTION 



The frog was now left in a cold and moist place until the following morning, when it was 

 found jumping about actively, with its heart contracting forty-eight times per minute. It 

 continued in very much the same condition for other two days, when it was killed. 



This experiment is especially interesting because of the very near approach 

 to death that was made. A decided effect was produced on the heart's action, 

 as it was reduced in frequency by from seventy to eighty beats in the minute : 

 respiratory movements were stopped ; reflex spinal action was completely pre- 

 vented ; and the spinal motor nerves were, for many minutes, paralysed : and yet 

 the animal revived ; and regained all its lost functions except that of the 

 heart, which only partially recovered itself. Such a result could never have been 

 obtained with a warm-blooded animal, as death would soon have been produced 

 by asphyxia, however long the heart might continue to contract. It is well known 

 that the frog may live for many days after the removal of its lungs, as the respira- 

 tory function of those organs is shared in by the skin of this animal. The effects 

 of the poison that was given in this case — and the dose was a very small one 

 in proportion to the weight of the frog — had gradually disappeared, and the dif- 

 ferent tissues had returned to their former vitality, after having been acted upon for 

 some time by a nearly normal blood-stream. Had the circulation ceased, or had 

 the effects on the tissues been greater, and, therefore, more permanent, this return 

 from pseudo-death could not have occurred. 



Experiment XLV1TI. — (Temperature of Laboratory, 58° F.) 

 The heart of a frog, weighing 396 grains, was exposed. After allowing a few minutes for 

 recovery from shock, the number of the cardiac contractions was determined at intervals of five 

 minutes, during twenty minutes, and found to vary little from forty-two beats per minute. One 

 grain of extract, in a few drops of water, was then injected into the subcutaneous tissue of each 

 thigh (two grains in all). 

 2 minutes afterwards, cardiac contractions = 36 per min. 

 4 = 24 



r Contractions seem feeble, and heart 

 6 „ „ = 20 „ <. is not so pale during systole as is 



X 



normal. 



8 „ „ = 17 „ 



10 „ „ =17 „ 



1 r, _ i r f Heart walls seem nearly as dark 



I during systole as during diastole. 



14 ., „ =14 „ 



16 „ ,, =14 „ 



18 „ ,, = 15 „ Frog is helpless and flaccid. 



20 „ „ =14 „ 



J- Almost no difference of colour during 

 25 „ „ = 14 „ ) systole, and a great prolongation 



30 „ „ =12 



35 „ „ = 13 



40 „ „ =12 



45 „ .. =8 



{ of diastole. 



f The ventricular contractions seem 

 I more feeble than the auricular. 



