370 



SCIENTIFIC THOUGHT. 



Vagaieness 



of biological mocleni 



theories. 



living 



No theory of the nature and origin of life has gained 

 universal acceptance : the very alphabet of biology, or 

 the science of life, has still to be written. We fancy 

 we possess some knowledge of certain forms or processes 

 which are common to all living matter, but the descrip- 

 tion of these has to be kept in the most general, not to 

 say the vaguest, terms : quite unlike the rudiments of 

 other scientific theories which deal with mathematically 

 defined conceptions expressed in distinct language and 

 formulae. 



For instance, if we take one of the best founded of 

 biological theories — the cellular theory ^ of 

 matter — we notice that the pretty definite 

 description which the early supporters of this theory — 

 Schleiden and Schwann — gave of this morphological 

 unit of vegetable and animal structvire has been dis- 

 placed by much vaguer descriptions. Schleiden and 



^ The history of tlie cellular 

 theory has been written from vari- 

 ous points of view in all the three 

 languages. I give the titles of a 

 few out of the great abundance 

 of excellent treatises. Foremost 

 stands the work of Prof. Oscar 

 Hertwig of Berlin, ' The Cell : 

 Outlines of General Anatomy and 

 Physiology.' English transl. by 

 Campbell (1895). Then there is 

 the more recent book by Prof. 

 Valentin Hiicker of Freiburg, 

 ' Praxis und Theorie der Zel- 

 len- und Befruchtungslehre ' (Jena, 

 1899). In the French language 

 we have the great compendium of 

 biological theories by M. Yves 

 Delage, ' La Structure du Proto- 

 plasma et les Theories sur I'Hdr- 

 edite,' &c. (Paris, 1895). In English 

 we have the valuable treatise of 

 Prof. E. B. Wilson, 'The Cell 



in Development and Inheritance ' 

 (1896), and the excellent little work 

 of Pnif. James Arthur Thomson, 

 'The Science of Life' (1899). Of 

 high importance are also the older 

 works of the great master and 

 brilliant expositor in biological 

 science, Claude Bernard, notably 

 his celebiated lectures entitled 

 " Lecons sur les Phenomenes de la 

 vie communs au.x animaux et aux 

 v(5g(5taux" (1878 and 1879), which 

 every j'^i'^^-'^ophical student of 

 biology should read, as well as his 

 excellent posthumously published 

 little work, ' La science experi- 

 mentale,' 1890. Of him M. Dumas 

 says that he has " epuisd ses forces ii 

 I'etude du grand mystere de la vie, 

 sans pretendre a pen^trer toutefois 

 sou origine et son essence" ('Sci. 

 Exper.,' p. 6). 



