MODERN BIOLOGY 403 



Virchow's cellular pathological-theory has been of great importance 

 to the development of biology, owing to the fact that he established, as 

 no one else had done before him, the cell's character as an independent life- 

 unit. He denies any form of spontaneous generation, whether within the 

 organism or without in nature. Just as it is impossible for an ascaris worm 

 to arise out of intestinal slime or an infusorian out of decaying matter, so 

 it is not permitted in the physiological or pathological tissue-theory for a 

 cell to be constructed " aus irgend einer unxelligen Substanz,." And he continues: 

 Wo eine Zdle entsteht, da muss eine Zelle vorausgegangen sem, ebenso ivie das Tier 

 nur aus dem Tiere, die Pfian^e nur aus der Pflanze entstehen kann." It is this prin- 

 ciple of cell multiplication, and thereby also of the cell's role in the organ- 

 ism as a whole, that represents Virchow's great contribution to the history 

 of biology. He himself applied his principle mostly to the sphere of path- 

 ology, in which he created with its aid a new theory of the origin not only 

 of tumours and other new growths, but also of purulent bodies. Otherwise, 

 his conception of the cell was in no way original; he mentions as its neces- 

 sary components the membrane and the nucleus, and considers its other 

 "fluid" contents to be less essential. In his general conception of the vital 

 phenomena Virchow is to a certain extent undecided; on the one hand, he 

 declares that there is a special life-force, that life is not a mechanical result 

 of the molecular forces of the bodily parts, while, on the other hand, he 

 holds that this life -force is probably of mechanical origin. Throughout his 

 life Virchow was of a very pugnacious disposition and used to defend his 

 views with great vehemence; with Haeckel in particular — once his own 

 pupil — he entered into violent controversies, not only on scientific, but 

 also on social questions, which both disputants were strongly inclined to 

 confuse with one another. But these disputes belong to the next era. 



The modern conception of the life and component parts of the cell was 

 founded by Max Schultze, a man who, in spite of a short life, made a last- 

 ing name in the history of biology. Max Johann Sigismund Schultze was 

 born at Freiburg in 1815 and studied at Greifswald (his father had been pro- 

 fessor of anatomy in both places), and he also attended the lectures of 

 J. Miiller in Berlin for a short time. He was at one time a lecturer at Halle 

 and from there was appointed to a professorship at Bonn. He worked with 

 success there, but died in 1874. 



Schultze's field of activities was very extensive; he devoted himself to 

 microscopical subjects in a number of animal classes. Specially famous are 

 his writings on the single-celled animals, to which further reference will be 

 made later on; they form one of the foundations of his cell theory. Further- 

 more he carried out important investigations into the microscopical anatomy 

 of worms and molluscs; in the Vertebrata he studied the terminal rami- 

 fications of the nervous system, and made weighty contributions to the 



