NATURAL SELECTION 127 



driver being some impulse in themselves. Numerous roads lead 

 off on either side and it is impossible to say that any one is the 

 main road more than another. All these ways lie open, but the 

 elders, by example and persuasion, lead the young into some 

 road or roads swerving at no very great angle from that already 

 followed or into the'one that leads straight on. Since the young 

 are not allowed to follow their devious caprices, it is seldom 

 that individuals are found pressing into widely divergent paths. 

 And so the species does not waste itself by vaguely experiment- 

 ing in new directions. And hence, too, Natural Selection, a 

 policeman who lynches all who don't go the pace or who take 

 a wrong road, works in a limited field, among the masses that 

 crowd the track that continues the line already followed or others 

 that diverge but slightly from it : among these masses it acts 

 with the utmost stringency : the laggards are ruthlessly cut off, 

 and evolution goes rapidly on. 



This, I believe, fairly represents the process of evolution A possible 

 in the higher species. But the Lamarckian may fairly enter demurrer 

 a demurrer and say : " Low down in the animal scale, the new 

 principle can work but feebly, if at all. There Natural 

 Selection acts directly on the individual from the moment of 

 his birth or the moment of the depositing of the egg. And 

 yet there have been developed forms as high as the newt and 

 the lizard an enormous advance from the lowest types. Can 

 Natural Selection have achieved all this ? If not, we must find 

 something that will assist it at every stage from the bottom 

 to the top ; not a principle which does not begin to operate 

 till the higher levels have been already attained." 



This objection certainly requires answering. Let us recur to 

 our simile which represents a species as a herd driven along a 

 road from which many roads lead off. If the elders do not guide 

 the young, there will be perpetual deviations, most of them 

 ending in wholesale destruction till some guiding tendency 

 develops and is fostered by Natural Selection. This guiding 

 tendency is rigid instinct and even that does not prevent a 

 slaughter, mainly during infancy, enormously above what takes 

 place among the higher classes of animals. As the crowd 



