THE PULSE-RATE IN VERTEBRATE ANIMALS 67 



of individuals. It is of course highly desirable that the correct 

 average should be known for every case, but it is difficult to get 

 people to make large collections of facts and it is debateable in 

 how far their doing so is a thing to be encouraged, so long as 

 the interest attaching to them is not in evidence. The following- 

 tables, if they serve no other purpose, at least indicate the sort 

 of value which would attach to a large collection of these 

 particular facts. 



TABLE I. Birds 



The table for birds shows us at a glance that, roughly, the 

 smaller the bird and therefore the greater the surface relatively 

 to the mass, the larger is the amount of oxygen consumed or 

 rather of carbon-dioxide given off, by a unit of weight in unit 

 time. If the rate of supply of oxygen to the tissues is greatest, 

 as it ought to be, in those in which the oxidation processes 

 take place most rapidly, we should expect the pulse-rates to vary 

 directly with what we take as a measure of these processes, so 

 long as the relative volume of blood expelled with each beat is 

 the same. Since the relative heart-size varies we should expect 

 to find a reciprocal relation between pulse-rate and relative 

 heart-size dependent upon the rate at which oxidation processes 

 occur. Where we have these data, or a measure of them, 

 the table shows us that this is the case. Thus comparing the 

 pigeon and the sparrow and knowing the pulse-rate of the pigeon, 



we should expect that of the sparrow to be — ~ = 6q^ 



in consideration of the different metabolisms, but to be 

 69 3 X 1-5 _ 

 1-36 



770 per minute in consideration also of the different 



