MEASURES OF VITAL TENACITY. 541 



factured in several qualities, the higher grades of which are eminently 

 suitable for casting purposes, have a close, steel-like surface, are sus- 

 ceptible of a high polish, are hard and tough, and possess great tensile 

 strength. 



MEASURES OF VITAL TENACITY. 



Br Dr. B. W. RICHARDSON, F. R. S. 



IN the observations which I have made on animals passing into 

 death by the lethal process, nothing has impressed me more than 

 the curious differences of vitality or vital values of different animals. 

 The differences are so great they seem almost inexplicable, and in 

 many respects they are so. To some extent, however, they come 

 under law, and we may therefore hope that by carefully continued 

 research what is now difficult and involved may be rendered, in time, 

 simple and perfectly clear. 



The first series of observed facts relate to vital differences in ani- 

 mals of different species. In illustration I may take the cat and the 

 dog. Between these animals the distinction of vitality exists irrespect- 

 ively of age, and of all other conditions and circumstances of which 

 I can gather information. 



Of the cat it is commonly said that it has nine lives. By this say- 

 ing nothing very definite is meant beyond the opinion that under vari- 

 ous kinds of death the cat lives much longer than other animals that 

 have to be killed by violent means. When any question is asked of 

 the police or of other persons who have to take the lives of lower ani- 

 mals, they tell you, without exception, according to my experience, 

 that the cat is the most difficult to destroy of all domestic animals, 

 and that it endures accidental blows and falls with an impunity that 

 is quite a distinguishing characteristic. 



The general impression conveyed in these views is strictly correct 

 up to a certain and well-marked degree. By the lethal death, the 

 value of the life of the cat is found to be, at the least, three times the 

 worth of the dog. In all the cases I have seen in which the exactest 

 comparisons were made, the cat outlived the dog. A cat and dog of 

 the same ages being placed in a lethal chamber, the cat may, with 

 perfect certainty, be predicted to outlive the dog. The lethal cham- 

 ber being large enough to hold both the cat and the dog, the vapor 

 inhaled by the animals being the same, with every other condition 

 identical, this result, as an experimental truth, may be accepted with- 

 out cavil. 



The differences, always well marked, are sometimes much longer 

 than would be credible in the absence of the evidence. I have once 

 seen a cat, falling asleep in a lethal chamber in the same period as a 

 dog, remain breathing, literally, nine times longer, for the dog died 



