188 The Evolution of Botany. 



as to Sprengel. Treviranus's views on phytotomy seem to 

 have been the basis for the theories which Mohl propounded 

 later, and which led to his (Mohl's) discovering the pri- 

 mordial utricle. Mohl, too, worked a great deal with the 

 microscope, and published a number of works on the anat- 

 omy of the ferns and on the anatomy of the cycas and 

 palm stem. His scientific examinations advanced every de- 

 partment of botany, but phytotomy especially. The scleren- 

 chymatic tissue was the object of the most minute and suc- 

 cessful study by him. Mohl was a thorough evolutionist, 

 who saw in all things evidence in behalf of natural develop- 

 ment. 



The work in microscopical investigation having been so 

 successfully carried on, soon solicited the aid of such scien- 

 tists as Meyen, Schleiden, Schwann, linger, and many others, 

 who continued the work, and to whom, with the previous 

 workers, may be accredited the development which plant 

 anatomy has reached to-day. 



Plant physiology, now again taken up by Bonnet, Saussure, 

 Duhamel du Monceau, Dutrochet, Senebiere, Knight, and 

 others, made big progressive strides, by the aid of the fund 

 of anatomical knowledge, the result of the labor of the men 

 just mentioned. Not only in the latter respect was physiol- 

 ogy advanced, but also very materially by the development 

 and application of chemistry. Boussingault and Liebig, the 

 latter more especially, investigated the chemistry of plants, 

 and determined the chemical processes going on within 

 them. Liebig proved that plants needed certain chemicals in 

 their food, and showed how they derived them from the soil. 

 The knowledge he thus gained led to the use of artificial 

 fertilizers, which restore the utility, for agricultural pur- 

 poses, of soil deprived of its chemical constituents by many 

 successive crops. 



To Goethe's views and studies regarding the metamor- 

 phosis of the plant, and to the works of De Candolle, Eobert 

 Brown, Schimpers, A. Braun, and others, we owe the origin 

 and development of the morphology of plants. A. Braun 

 was very diligent in his endeavors to develop plant mor- 

 phology, and it was he who discovered the regular arrange- 

 ment of the leaves upon the stem phyllotaxis. The crypto- 

 gamic morphology was the subject of his late studies ; he 

 studied especially the characeae. R. Brown busied himself 

 in the same field ; he determined the morphological relations 

 in the organization of the seeds of monocotyledonous and 



