490 



SCIENCE. 



[N. S. Vol. XV. No. 378. 



If no two individual living beings are 

 alike; if the stability of biological types 

 means that the aberrant have been exter- 

 minated in the struggle for existence, and 

 if the modification of a type is an indica- 

 tion of a change in the standard of exter- 

 mination; are not inlieritance and varia- 

 tion two partial and imperfect views of 

 the selective process^ When the embryol- 

 ogist seeks in the germ for the material 

 basis of inheritance, and for the mechan- 

 ism of variation, is he not searching for 

 something which has no independent exist- 

 ence? Must he not seek, in the interrela- 

 tions between living beings and their 

 environment, and not in the living beings 

 as they are in themselves, for that of which 

 he is in search? Do not they who think 

 that natural selection must be supplied 

 with the raw material by a mechanism for 

 variation before it can do anything, both 

 personify the selective process and forget 

 the diversity of nature? 



17. Does physical analysis give an ade- 

 quate account of the organization of living 

 bodies? 



Physical analysis resolves organized 

 beings into organs and tissues and cells 

 and physiological units, but does this 

 analysis give an adequate account of 

 organization ? 



The bodies of two allied animals are 

 alike in structure. They are composed of 

 organs which are said to exhibit funda- 

 mental unity behind superficial diversity, 

 for they are practically identical in his- 

 tory, and for most of the purposes of the 

 anatomist and the physiologist and the 

 zoologist. From this point of view, and 

 from many others, they are identical in 

 structure, yet the differences between them 

 do not cease to be because they do not con- 

 cern us, nor because they escape our 

 notice, for while the identity is real and 

 important and significant, it has no ab- 

 stract, or independent, reality. 



' Were the heart of one man, ' says 

 Maudsley, ' to be placed in the body of 

 another, it would probably make no differ- 

 ence in the circulation of the blood, but it 

 might make a real difference in the temper 

 of his mind.' Does not the analogy of 

 nature lead us to ask whether it might not 

 be expected to make a difference in the cir- 

 culation of his blood as well as in the tem- 

 per of his mind? If our knowledge of 

 hearts were as minute and individual as 

 our knowledge of men, might we not need 

 a proper name for each heart as much as 

 we need one for each man? 



If the interest of the histologist in the 

 resemblances between the tissues of one 

 animal and those of another leads him to 

 lose sight of their constitutional differ- 

 ences, he is in danger of mistaking an ab- 

 straction for a reality, for while the scien- 

 tific basis of histology in the resemblances 

 between the tissues of one animal and 

 those of another is real and significant, it 

 has no abstract, or independent, reality. 



"Prom the morphological standpoint," 

 says Hertwig, quoting from de Vries, ' ' we 

 may properly regard the cell, apart from 

 the organism, as an individual, biit we 

 must not forget that it is by abstraction 

 that we do so. Physiologically the cell is 

 an individual only when actually isolated 

 and independent of an orgauism. From 

 this standpoint, every abstraction is a 

 blunder." 



When we say a multicellular organism 

 is a unit, must we not also say what are 

 the relations with refei'ence to which it is 

 a unit? When we say its constituent cells 

 are units, must we not also say what are 

 the conditions with reference to which they 

 are units ? Have we any way to find these 

 things out except scientific discovery? 



18. 7s cell-differentiation inherent or 

 induced? 



A thoughtful and distinguished natural- 

 ist tells us that while the diiferentiation of 



