170 THE CELL-THEORY 



as a whole, how it lived and nourished itself, and they 

 studied cells and sieve-tubes, wood fibres and tracheae with 

 a view rather to finding out their functions and their 

 significance for the life of the plant than to discovering 

 the minutiae of their structure. The same attitude was 

 taken up by the few botanists who in the iSth century 

 paid any heed to the microscopical anatomy of plants. For 

 C. F. Wolff, 1 the formation of cells was a result of the 

 secretion of drops of sap in the fundamental substance of 

 the plant, this substance remaining as cell-walls when cell- 

 formation was completed no idea here of cells as units of 

 structure. 



In the early ipth century, interest in plant anatomy 

 revived somewhat, and much work was done by Treviranus, 

 Mirbel, Moldenhawer, Meyen and von Mohl.' 2 As a result of 

 their work the fact was established that the tissues of plants 

 are composed of elements which can, with few exceptions, be 

 reduced to one simple fundamental form the spherical 

 closed cell. Thus the vessels of plants are formed by 

 coalescence of cells, fibres by the elongation of cells and the 

 thickening and toughening of their walls. At this time, 

 interest was concentrated on the cell-wall, to the almost 

 total neglect of the cell-contents ; the " matured framework " 

 of plant cells, to use Sach's convenient phrase, was the chief, 

 almost the sole, object of study. And it was natural enough 

 that the mere architecture of the plant should monopolise 

 interest, that the composition of the tissues out of the cells, 

 and the fitting together of the tissues to form the plant 

 should awaken and hold the curiosity of the investigator; 

 even the modifications of the cell-walls themselves, their 

 rings and spiral thickenings and pits, offered a fascinating 

 field of enquiry. 



The idea that the cell-contents might show a characteristic 

 and individual structure had hardly dawned upon botanists 

 when Schleiden published his famous paper, In'ifni^'c r-itr 

 Phytogenesis? Schleiden's theme in this paper is the origin 



1 Theoria generationiS) Halae, 1759. 



- See J. v. Sachs, Geschichtc dcr Botanik, book ii., Eng. Trans., 2nd 

 iinpr., 1906. 



3 Miiller's Archiv, pp. 137-76, 1838. 



