42 INTRODUCTION. 



been well grounded ; and new paths were soon struck out, each 

 of which, leading into some region previously unexplored, soon 

 cleared the way to others which became alike productive ; thus 

 laying open an almost unlimited range of inquiry, which the 

 time that has since elapsed has served rather to extend than to 

 contract, and which the labor that has been devoted to it has 

 rather amplified than exhausted. A slight sketch of what has 

 already been accomplished by the assistance of the Microscope, 

 in the investigation of the phenomena of Life, seems an appro- 

 priate Introduction to the more detailed account of the instru- 

 ment and its uses, which the present Treatise is designed to 

 embrace. 



The comparative simplicity of the structure of Plants, and the 

 relatively lai'ge scale of their elementary parts, had allowed the 

 Vegetable Anatomist, as we have seen, to elucidate some of its 

 most important features, without any better assistance than the 

 earlier Microscopes were capable of supplying. And many of those 

 humbler forms of Cryptogamic vegetation, which only manifest 

 themselves to the unaided eye when hy their multiplication they 

 aggregate into large masses, had been made the objects of care- 

 ful study, which had yielded some most important results. Hence 

 there seemed comparatively little to be done by the Mieroscopist 

 in Botanical research; and it was not immediately perceived 

 what was the direction in which his labors were likely to be 

 most productive. Many valuable memoirs had been published, 

 from time to time, on various points of vegetable structure; the 

 increased precision and greater completeness of which, bore 

 testimony to the importance of the aid which had been afforded 

 by the greater efficiency of the instrument employed in such re- 

 searches. But it was when the attention of Vegetable Phj'siolo- 

 gists first began to be prominently directed to the history ot 

 developynent, as the most important of all the subjects which pre- 

 sented themselves for investigation, that the greatest impulse 

 was given to Scientific Botany ; and its subsequent progress has 

 been largely influenced by that impulse, both in the accelerated 

 rate at which it has advanced, and in the direction which it has 

 taken. Although Robert Brown had previously observed and 

 recorded certain phenomena of great importance, yet it is in the 

 Memoir of Prof. Schleiden, first published in 1837, that this new 

 movement may be considered to have had its real origin ; so 

 that, whatever may be the errors with which his statements 

 (whether on that occasion, or subsequently) are chai'geable, there 

 cannot be any reasonable question as to the essential service he 

 has rendered to science, in pointing out the way to others, on 

 whose results greater reliance may be placed. It was by Schlei- 

 den that the fundamental truth was first broadly enunciated, that 

 as there are as many among the lowest orders of Plants, in 

 which a single cell constitutes the entire individual, each living 

 for and hy itself alone, so each of the cells, by the aggregation of 



