30 DARWINISM AND EVOLUTION 



the existence of parasites, those degraded organisms that devour the 

 vital juices of beings infinitely higher than themselves, and inflict 

 measureless pain not only on our own persons, but on the sentient 

 bodies of our mute companions. It is hardly too much to say 

 that every animal, if not every man, is infested by them. " They 

 " crawl upon his surface, they burrow beneath his skin, they nestle 

 " in his entrails, they float in his blood, they riot and propagate 

 " their kind in every part of his frame." Organisms so excessively 

 minute as to require the highest power of the microscope for 

 their definition, the amount of whose conscious enjoyment must 

 be almost nothing, produce, by their mere multiplication in the 

 bodies of vertebrate animals, the fevers, inflammations, and even 

 the consumption that cause such misery and make such havoc 

 upon the earth. It would have tried the metal of the courageous 

 priest now no more, to assert that these pests were the result of 

 a special act of a benevolent Creator, and that they all followed 

 Noah into the ark at the time of a universal deluge. But of two 

 things, special creation and evolution, we must choose one. 



THE SENSES. 



^Phe evolution of the senses must be mentioned, though time 

 -*- fails us to consider it adequately. 



Sensory organs are means by which the forces exerted by sur- 

 rounding bodies are transmuted into affections of nerve — by 

 which Dynamosis may become Neurosis, — and they are all 

 specialised portions of the common integument. A hair is a 

 prolongation of skin, and a vibrissa, or a stiff hair like a cat's 

 whisker, is an organ of touch. And the stalked eye of the Crus- 

 tacean is really a transformed limb with a sensitive tip. In order, 

 however, to lead up to the evolution of mind, to follow Neurosis 

 into Psychosis, we must describe more fully the evolution of the 

 sense of sight. 



In some animals of the humblest type, especially those which 

 are quite transparent, the whole body is affected by light, as 

 opposed to darkness. Professor Ray Lankester was of opinion 

 that the eye of the vertebrates began to be evolved at the time 

 when the ancestral head was completely transparent. It is known 



