for hardening, sclerosis, and arterial sclerosis is one 

 of the most marked and striking characteristics of 

 old persons. Now when the arteries become thus 

 stiffened, it requires a greater force and greater effort 

 of the heart to drive the blood through them, and in 

 response to this new necessity, the heart becomes 

 enlarged in an effort of the organism to adapt itself 

 to the new unfavourable condition of the circulation 

 established by age. But the power of the heart be- 

 comes inferior along with the hypertrophy or enlarge- 

 ment of the organ and we see that in the old, in 

 order to make up for the feebleness of the enlarged 

 heart, it beats more frequently. In other words, the 

 pulse rate in the old person increases. 1 We find, for 

 instance, that at the time of birth the pulse is at the 

 rate of 134 beats to a minute. It rises slightly during 



1 My friend, Professor W. T. Porter, has had the kindness to compile the 

 accompanying table for me. showing the pulse frequency from one to eighty 

 years. For the first two months after birth the rate is about 130, after the 

 third month, 140. The foetal rate is 135 to 140. 



. Mean . Mean . Mean 

 Frequency Frequency Frequency 



0- i 134 13-14 87 25-30 72 



1- 2 in 14-15 82 30-35 70 



2- 3 108 15-16 83 35-40 72 



3-4 108 16-17 80 40-45 72 



4-5 103 17-18 76 45-50 72 



5-6 98 18-19 77 50-55 72 



6- 7 93 19-20 74 55-6o 75 



7- 8 94 20-21 71 60-65 73 



8-9 89 21-22 71 65-70 75 



9-10 91 22-23 70 70-75 75 



lo-n 87 23-24 71 75-8o 72 



i [-12 89 24-25 72 80 and over 79 



12-13 88 



