54 



making dissections under the microscope, and notes of the 

 the results, of every plant collected in ray rural excursions. 

 These researches were undertaken mainly for the purpose 

 of comparing the intimate structure of plants and aniinnls ; 

 and the discovery of the value of this structure in syste- 

 matic botany was quite an incidental and unexpected result. 

 My own observations had not been long prosecuted when 

 several examples were found that seemed to justify the 

 truth of Schleiden's remark as to how little hope there is, 

 without a study of the fundamental principles of develop- 

 ment, of much further aid to systematic botany from mere 

 anatomy. But, when a large mass of my notes has been 

 collated, it plainly appeared that the mature structure and 

 function of the plant-cells would be far more useful in this 

 way than was supposed by the eminent German botanist. 

 Thus, for example, uo single instance of any species be- 

 longing to the orders OnagracesB, Galiacene, and Balsa- 

 minacene was without a note of the presence of raphidian 

 cells. And, conversely, a single order, e.g., Hydrochari- 

 daceae, in which these cells were never seen at all, would 

 be surrounded by its allied orders in which raphidian cells 

 always appeared abundantly. The cells of the pollen, epi- 

 dermis, pith, and of many tissues of various other orders of 

 plants, were also found to give constant and diagnostic 

 characters. Thus it was that this subject forced itself on 

 my attent'on; and, afterwards, numberless experimental 

 trials satisfied me that the raphidian form of cell-life is, in 

 particular, an essential and intriiisic, a distinct and truly 

 characteristic, phenomenon throughout the life of the 

 plants exhibiting it, and withal clearly a sure and con- 

 stant result of that life ; while the same character is as 

 certainly wanting in the species of allied orders. These 

 raphidian cells were proved to be present in the ovule, in 

 the seed-leaves, and thenceforth throughout the succeeding 

 leaves and a large part of the intertexture of the frame of 

 the species of several orders, somo of which have been just 

 specified. 



