CHAPTER V. 



MORPHOLOGY AND SYSTEMATIC BOTANY UNDER THE 



INFLUENCE OF THE HISTORY OF DEVELOPMENT AND THE 



KNOWLEDGE OF THE CRYPTOGAMS. 



1840-1860. 



IN the years immediately before and after 1840 a new life 

 began to stir in all parts of botanical research, in anatomy, 

 physiology, and morphology. Morphology was now specially 

 connected with renewed investigations into the sexuality of 

 plants and into embryology, and attention was no longer con- 

 fined to the Phanerogams but was extended to the higher and 

 later on to the lower Cryptogams. These researches into the 

 history of development first became possible, when von Mohl 

 had restored the study of anatomy, and Nageli had founded and 

 elaborated the theory of cell-formation about the year 1845. 

 The success of both these enquirers was due to the previous 

 development of the art of microscopy ; it was the microscope 

 which revealed the facts on which the foundations of the new 

 research were laid, while its promoters at the same time 

 started from other philosophical principles than those which 

 had hitherto prevailed among botanists. Investigation by 

 means of the microscope enforces on the observer the very 

 highest strain of attention and its concentration on a definite 

 object, while at the same time a definite question to be 

 decided by the observation has always to be kept before the 

 mind ; there are sources of error on all sides to be avoided, 

 and possible deceptions to be taken into consideration ; the 



