F. W. Head ley 355 



of those who have serviceable lungs. Thus individuals tide 

 over a crisis by improving their natural gifts by exercise ; 

 without such Lamarckian methods, they would not be equal to 

 the emergency. At the same time, there is a selection of those 

 who can thus improve themselves. When the next drought 

 comes probably further variations in the same direction have 

 arisen, and there would have been an opportunity for this, but 

 for those modifications due to exercise which secured a respite 

 for the species. And thus modifications though not transmitted 

 to the next generation are the prelude to variations similar in 

 tendency to themselves. Before going further, I must say 

 something to justify the above illustration. It is probable that 

 the lung was, in origin, a fully-developed swim-bladder. But 

 a fully-developed swim-bladder may be only rudimentary when 

 regarded as a lung. There was need of exercise to make it 

 serviceable and give it selection-value in this capacity. I have 

 felt justified, therefore, in speaking of it for the sake of sim- 

 plicity as a rudimentary lung. 



" One more instance. I imagine the Wapiti deer, or rather 

 one of his progenitors, this is the old puzzle set to Neo- 

 Darwinians by Mr. Herbert Spencer,- - developing great antlers 

 through the accumulation of congenital variations by Natural 

 Selection. What if the muscles and ligaments of the neck 

 and of all the cooperative machinery did not grow strong 

 through favourable variations during the same period ? The 

 answer is plain enough ; even without the help of Natural 

 Selection the organism will be able to make shift for a time. 

 Muscles can be strengthened by use during the lifetime of the 

 individual. How much can be done in this way if we begin, 

 say in our teens, and exercise certain muscles regularly for half 

 an hour a day ! How great would be the result if we exer- 

 cised them each day during the whole time that we were on our 

 legs ! All day the stag was carrying his antlers, and his muscles 

 were acquiring the strength that was needed. But when the 

 antlers in the course of many generations had grown big, males 

 that were born without specially adapted muscles to carry 

 them would not be likely to be lords of the herd. So that here, 



