The Evolution of Botany. 185 



As an illustration of Dillenius's diligence and accuracy may 

 be mentioned the fact that, in the neighborhood of Giessen 

 alone, he discovered more than 200 species of mosses, of 

 which 140 were theretofore unknown. Of fungi he found 

 160, of which 90 were not known before. 



About this time is recorded the beginning of the experi- 

 mental investigation into the physiology of plants, in which 

 field St. Hales was the pioneer. He discovered the function 

 of the sap in plants, and his experiments concerning the ris- 

 ing of the sap in trees are still celebrated. 



In the following period the activity of botanists was main- 

 ly directed to the development and application of Linnasus's 

 system. The increasing and widening knowledge of species 

 was aided by the publication and continuation of Linnaeus's 

 Genera and Species Plantarum, to which Schreber, Willde- 

 now, Yahl, Persoon, Romer, Schultes, Sprengel, Presl, D. 

 Dietrich, and H. Richter contributed largely. 



The study of the lower orders of plants was again resumed, 

 in the beginning of this century, by Presl, whose works on 

 the grasses and ferns are very interesting, and by Persoon 

 and Sprengel, who were the first to describe the fungi. Per- 

 soon arranged and classified them into species and genera. 



Late in the eighteenth century Kolreuter and Schmidel 

 began to study the organs of fructification of the lower cryp- 

 togams (flowerless plants). Their works were factors in 

 broadening the scope of cryptogamous botany. 



The introduction of Linnseus's artificial system of classifi- 

 cation led botanists to abandon their speculations on classi- 

 fication for a while, to devote themselves to the study of 

 plants individually again, and, as we have seen, a period fol- 

 lowed in which the investigation and observation of scien- 

 tists were directed to the fuller development of the lower 

 orders. The higher orders, though, were not neglected in 

 the mean time, and new plants were continually discovered 

 and new facts learned concerning those known. The vast 

 accumulation of known species and the rapid development 

 botany was enjoying soon convinced botanists that the Lin- 

 naean system, too, was becoming insufficient to answer its 

 purpose, and that, sooner or later, a natural system would 

 have to be instituted which alone could ultimately meet all 

 the requirements. 



Adanson, Oder, and Gartner made several efforts to institute 

 such a system, but all failed. Adanson in one of his works 

 devoted much time and labor to a system which was con- 



