ON THE MORPHOLOGICAL VIEW OF NATURE. 265 



to these amorphous 1 constituents, and chemical investi- 

 gations as to their composition were added to the previous 

 microscopic dissection. The purely morphological view 



lated into German by a number of 

 botanists, and edited in five volumes 

 between 1825 and 1834 by Nees 

 von Essenbeck. He did not collect 

 his original ideas into any great 

 work or propound a new system of 

 classification as did Jussieu and De 

 Candolle, whom he equals in scien- 

 tific importance ; his valuable gen- 

 eralisations were given occasion- 

 ally in his numerous monographs. 

 Sachs considers him more advanced 

 than the two great rivals just 

 named, inasmuch as he had an 

 appreciation of questions of devel- 

 opment which they lacked (' Gesch. 

 d. Botanik,' p. 121). Humboldt 

 called him " botanicorum facile 

 princeps," and succeeded in procur- 

 ing for him, through his influence 

 with Sir Robert Peel, a pension of 

 200 per annum. 



1 The definition of a cell i. e. , of 

 the morphological or form-element 

 of organised matter, as consisting 

 of a membrane, a cell content, a 

 nucleus, and a nucleolus stood in 

 contrast with Felix Dujardin's de- 

 scription, in 1835, of a living sub- 

 stance which he met with in his 

 researches in lower animal life, and 

 which he had called "sarcode." In 

 the place of this name the observa- 

 tion of Dujardin being little noticed 

 Von Mohl, after having for a time 

 accepted the erroneous theory of 

 Schleiden and Schwann as to cell- 

 formation, introduced the term 

 " protoplasma," which has been re- 

 tained in science as the name of the 

 elementary constituent of all living 

 matter with very varying defini- 

 tions, according to the different 

 observations of animal or vegetable 

 organisms and the increasing powers 

 of the microscope ; this having re- 

 vealed structures where before only 



formless, amorphous substance had 

 been observed. The history of 

 these fluctuations of opinions and 

 definitions can be read both in the 

 older histories (Sachs, Carus) and 

 the more recent accounts. Among 

 these numerous expositions, see 

 especially Yves Delage, ' L'He"redite" 

 et les grands problemes de la Bio- 

 logie,' 1895, p. 19, &c.; 0. Hertwig, 

 ' The Cell, ' translated from the 

 German by H. J. Campbell, 1895 ; 

 and the most recent work by Dr 

 Val. Hacker, ' Praxis und Theorie 

 der Zellen und Befruchtungslehre,' 

 Jena, 1899, p. 10, &c. The cellular 

 theory has gained enormously in 

 importance and in popular esteem, 

 as has also the study of all micro- 

 organisms, through its application 

 to medicine and hygiene. In 1847 

 Rudolph Virchow founded his cele- 

 brated "cellular pathology," com- 

 bining the mauy beginnings of the 

 cellular theory which had been 

 laid by others, in his famous axiom 

 " omnis cellula e cellula." He gave 

 up the theory of the free forma- 

 tion of cells, proclaimed the doctrine 

 of the genesis of cells even patho- 

 logical ones by cell-division, and 

 adopted Goodsir's theory of the 

 uninterrupted filiation of the ele- 

 ments of all living matter, of the 

 autonomous cells. As in general 

 biology, so also in cellular path- 

 ology, the last fifty years have 

 witnessed great controversies and 

 many special theories, one of the 

 chief difficulties having been to com- 

 bine the doctrine of the autonomy 

 or individuality of the cells with a 

 correct view of their filiation and 

 connected life. In spite of these 

 many changes and modifications, the 

 name of Schwann still stands at the 

 opening of every treatise on funda- 



