386 \V. F. FISKE. 



and evil if they appeared to be injurious and obnoxious. First we were called upon 

 to separate our friends from our foes, and then, on the basis of such knowledge, we 

 were to endeavour to oppress our enemies without oppressing our friends. 



But since we were recommended this course we have accepted, more or less 

 finally, the doctrines of Darwinism. AVe have come to believe that the many species 

 w'hich comi^ose a fauna and flora were not created in their present forms by super- 

 natural powers of good or of evil, but that they have acquired their present charac- 

 teristics through long-continued contact and association with each other and with 

 their physical enviromiient. We no longer believe that the world was created for 

 man's occupancy, but that man somehow^ contrived to fit himself into a world already 

 teeming with life. He, like every other species is a creature of environment, imposing 

 new conditions of life upon others as his evolution proceeds, and having new conditions 

 of life imposed upon him as their evolution proceeds. The factors which operate in 

 the natural control of species are largely identical with those which directed the evolu- 

 tion of these species into their present forms, and which continue to operate in a never- 

 ending process. The student in the natural control of contemporaneous species is 

 studying evolutionary processes at first hand. 



In such circumstances one would suppose that the promulgation and acceptance 

 of the philosophy of Darwin would have resulted in a complete revolution in our 

 methods for the acquisition and application of biological knowledge; but in so far as 

 entomology is concerned, this does not appear to be the case. When direct reference 

 to the Mosaic doctrine is eliminated from the introduction to Dr. Harris' treatise, that 

 which remains (as I have attempted to demonstrate) w^ould pass muster to-day. 



Our adherence to a doctrine which we admit to be antiquated is w^ell illustrated 

 by constant reference to parasitic and predatory species as the " natural enemie:^ " of 

 those other species upon which they depend for subsistence. The fact that the 

 individual parasite or predator is an enemy of the individual host or prey by no means 

 warrants the assumption that the parasitic species is the enemy of the host species. 

 Such implacable, hereditary enmity was implied by Mosaic doctrine, and was 

 thoroughly in accord wnth the conception of supernatural powers of good and of evil 

 competing for mastery ; but it is thoroughly out of accord with the Darwinian 

 hypothesis of good competing wdth good to prove w^hich is the better. The parasitic 

 species cannot be the enemy of its host species without becoming its own enemy by 

 the same act ; if it weaken its host, it weakens its ow^n chances of survival, and if it 

 succeed in destroying its host, it has destroyed all its own chances of survival. The 

 fittest parasite to survive must be the one w^hich not only refrains from injuring and 

 weakening its host, but which in some manner serves to benefit it. H the parasitic 

 species were literally the enemies of their host species, as is almost universally implied 

 by the phraseology employed in our literature, the fact alone W'Ould be sufficient to 

 invalidate the Darwinian hypothesis. 



The facts are really these : that one race or species of organism is injurious or 

 beneficial in its relations to another species, not in accordance with the characteristics, 

 habit and instincts of the individuals involved, but in accordance wdth the circum- 

 stances and conditions prevailing at the time and place which brings them into contact. 

 These circumstances and conditions are continually changing, with respect to both 

 time and locality. Examples without number might be adduced from my own 



