774 THE POPULAR SCIENCE MONTHLY. 



preserve a degree of immunity for exhausting exercises longer 

 than the average are those whose circulation has remained regu- 

 lar, and whose arteries have not yet begun to undergo sclerotic 

 degeneration. They are really younger than their age. Every 

 man, according to the happy expression of Cazalis, is " of the age 

 of his arteries/' and not of that which he deduces from his birth. 

 Taking a mean, we may say that after forty years a man ought to 

 abstain from exercises that induce shortness of breath. Instead 

 of exercises of speed, he should adopt those requiring bottom, for 

 which he will preserve a remarkable capacity. Race-horses which 

 have become incapable of enduring labor that involves speed may 

 for many years afterward perform excellent service at more mod- 

 erate paces ; they may even easily endure the paces of the hunt, 

 when they have to carry their rider for the whole day, but in 

 which the fundamental gait is not the gallop but the trot. So 

 man preserves to the extreme limits of mature age the faculty of 

 enduring a considerable labor for many hours, provided it is car- 

 ried on with moderation. Many of the best mountain guides are 

 approaching their sixties, and can easily tire young tourists. But 

 everybody has remarked that the most experienced guides that 

 is, the oldest ones go up very slowly, and that under that con- 

 dition they can walk for an indefinite time. They do this by 

 avoiding, through the moderation of their pace, the quickening 

 of their pulse and the imposition of an excess of work on their 

 heart. 



In 1870, when the dangers of the invasion called all French 

 citizens to take part, each one according to his ability, in the de- 

 fense of the country, national guards of the reserve were organ- 

 ized everywhere, in which all those who for any reason had not 

 been incorporated in the active service were enrolled. In the 

 exercises of these improvised battalions, men of very unequal 

 ages could be seen elbowing one another in the ranks. Many of 

 them, who had passed their fortieth year, but felt themselves still 

 "game," came to take part in the manoeuvres, and were never 

 behind in the long drill-marches. Generally, indeed, the elderly 

 men displayed a greater power of resistance than the younger 

 ones. But their superiority vanished as soon as the manoeuvres 

 took the form of quick movements. The " gymnastic step " was 

 the terror of these well-intending veterans ; after one or two min- 

 utes of the run they could be seen leaving the ranks out of breath, 

 while the younger ones, whom they had left behind on the long 

 marches, kept on for a considerable time without feeling any 

 obstruction to their breathing. Serious accidents were sometimes 

 produced in these movements, when they were commanded by too 

 zealous officers who forced the men to keep up their speed not- 

 withstanding the difficulty in their breathing ; and national 



