262 



SCIENTIFIC THOUGHT. 



46. 



Hugo von 

 Mohl. 



and it was also recognised that they were frequently 

 elongated into tubes or joined so as to form larger 

 vessels. In all these researches and descriptions para- 

 mount importance was attached to the form and com- 

 position of the framework of this cellular arrangement, 

 and only little to its contents. In fact, the historian 

 of botany^ characterises the period from 1800 to 1840 

 as that of the study of the cellular framework of plants. 

 The skeleton, as it were, of plant structure received 

 primarily the greater attention. In the course of these 

 researches, which, with a few important exceptions, were 

 all carried out in Germany, one point was permanently 

 settled, namely, that " the cell is the one fundamental 

 element of all vegetable structure." ^ No one did more 

 to establish this important fact than Hugo von Mohl, 

 whose name has been somewhat cast into the shade by 

 the more attractive writings of Schleiden. It was 

 Schleiden who first brought the new cellular theory 

 into popular recognition, not without an admixture of 

 errors, which had to be gradually eliminated in the 

 various controversies with which his name is connected. 



^ See Sachs, loc. cit., p. 276, &c. 

 This period finds its consummation 

 in the researches of Hugo von Mohl. 

 It begins with those of Brisseau 

 Mirbel, the first French author who 

 took up this line. His labours were 

 continued and criticised by a long 

 list of German naturalists. Sachs 

 also refers to the erroneous habit 

 these earlier phytotomists had of 

 getting their diagrams of what 

 they saw by the microscope made 

 by other persons who were sup- 

 posed to be impartial — a custom 

 fortunately abandoned by Mohl, 

 who in his drawings did not give 



" undigested copies of the objects 

 but his own impressions of them " 

 (p.^281). 



- Sachs assigns the final estab- 

 lishment of this principle to the 

 year 1831, and considers it as one 

 of Mohl's achievements, since, 

 although it had been already 

 announced by Sprengel and Mirbel, 

 it had not been sufficiently sup- 

 ported by observations. Even the 

 curious but antiquated idea, accord- 

 ing to which the spiral fibre formed 

 a fundamental part of plant struc- 

 ture, survived up to 1830 (p. 323). 



