270 



SCIENTIFIC THOUGHT. 



who did more than any other naturalist to base zoology, 



anatomy, and physiology on the foundation of the exact 



sciences, physics and chemistry, " assumed the existence of 



a vital force which, differing from physical and chemical 



forces, enters into conflict with them, and which in 



organisms acts the part of a supreme regulator of all 



phenomena according to a definite plan." l 



50. The insufficiency of a purely morphological description 



o" the mu"^ of living beings, the unsuccessful search for the morpho- 



phological 



logical elements out of which organisms are built up, as 

 crystals are formed out of the molecules intfyrantes of 

 Haiiy, led thinkers (up to the middle of the century) to 

 have recourse to older and vaguer conceptions, which, 

 under the name of archetypes, formative influences, vital 

 forces, &c., were destined to help where the purely 

 mechanical view would not suffice. This dilemma was 

 appropriately described somewhat later by one who 

 had earlier, perhaps, than any other thinker eman- 

 cipated himself from the influence of these fanciful 

 conceptions. Herbert Spencer in his ' Principles of 

 Biology,' published in 1863, expresses it in the fol- 

 lowing words : 2 - 



" If we accept the word ' polarity ' as a name for 

 the force by which inorganic units are aggregated into 



1 See Du Bois-Reymoud, "Ge- 

 dachtnissrede auf Johannes Miiller" 

 ('Reden,' vol. ii. p. 217). 



2 The ' Principles of Biology,' 

 from which this extract is quoted, 

 appeared in successive instalments, 

 beginning in January 1863. It is 

 well to note that this was before the 

 appearance of Haeckel's ' Generelle 

 Morphologic,' which bears the date 

 1866. It does not appear that 



Spencer has had any influence on 

 German science, though no doubt 

 many of the conceptions put 

 forward in the numerous treatises 

 of German biologists are anticipated 

 in Spencer's ' Biology,' notably in 

 his conception of the physiological 

 units as intermediate between com- 

 pound chemical molecules and 

 crystals on the one side, and cells 

 on the other. In the exhaustive 



