THE WORLD OF LIFE. 



643 



The eminent chemist, Sir A. H. Church, wanted a word to express 

 the following fact, and coined the term "Directivity" in 1862 "to 

 avoid the use of * force,' * energy,' &c., when describing in lectures on 

 organic chemistry the parallelism between the chemist directing in his 

 laboratory physico-chemical forces in the making of a true organic 

 compound and that mysterious something which employs the same 

 forces to make the same compound in the plant or animal." 



Dr. Wallace, is wrong, therefore, in saying such compounds are 

 made "always by the use of organic products," as, e.g. Alizarine 

 (madder) from coal-tar. Sir A. H. Church, on the other hand, says: 

 " Many compounds previously known only as products of animal and 

 vegetable life have now been made under the direction of the chemist 

 from purely inorganic sources, that is, from their elements, and 

 without having recourse to such substances as are derived from coal- 

 tar. It is to such compounds that I first used the term * Direc 

 tivity.' " 



Dr. Wallace endeavours to combine this " directive agency," as he 

 calls it, with natural selection; but they are mutually exclusive. He 

 described the chemist's procedure in making organic products, but 

 rightly adds : * * The more important of the constituents of living 

 organisms [e.g. Protoplasm] remain far beyond his powers of 

 synthesis."* 



Dr. Wallace notes that Professor Max Yesarne, while strongly 

 repudiating the idea of a " "Vital Force," " gives no clue whatever to 

 the existence of any directive and organizing powers such as are 

 absolutely essential to preserve even the unicellular organism alive, 

 and become more and more necessary as we pass to the higher animals 

 and plants, with their vast complexity of organs, reproduced in every 

 generation from single cells . . . till the whole body, limbs, sense, 

 and reproductive organs are built up in all their perfection of structure 

 and co-ordination of part, such as characterizes every living being! "f 



Why does he not go one step further, and apply this " directive 

 agency " to the evolution of changes of structure, to make them 

 become in adaptation to new conditions of hfe, i.e. Variations? 



He then illustrates this by the feathers of a bird, and describes the 

 hooking process by which the " barbicels " of one " barbule " chng 

 to those of the next, in order to make a rigid surface to the wing. 



Dr. Wallace adds: "What, then, is the selective or directing 

 power which extracts from the blood at every point where required 

 the exact constituents to form, here, bone-cells, there, muscle-cells, 

 &c.,&G.?l 



" Now in none of the volumes on the physiology of animals that 

 I have consulted can I find any attempt whatever to grapple with this 

 fundamental question of the directive power, that in every case, first 

 secretes, or as it were creates, out of the protoplasm of the blood, 

 special molecules adapted for the production of each material bone, 



* P. 329. t P. 294. 



X This will be found in my lecture on "Directivity," see p 534. 



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