126 Trans. Acad. Sci. of St. Louis. 



Linnaeus himself, in 1771, admitted 8551 species of plants, 

 of which more than nine-tenths belong to the most obvious 

 and grossly marked group, the flowering plants, which, with 

 the ferns, still represent the field of botany for uneducated 

 persons. The rapidity of progress in differentiating unrecog- 

 nized species and characterizing such as had remained unob- 

 served is shown by the increase of Linnaeus's scant 9,000 to 

 some 70,000 before the first quarter of the Nineteenth Cen- 

 tury had been passed, and, largely because of territorial ex- 

 ploration, the next half century produced even greater results 

 and the phenomenal interest in the interior of Africa evinced 

 during the closing decade of the century is to-day bearing 

 like fruit. With this activity in collecting and naming plants 

 came inevitably a progressive interest in the more and more 

 difficult and minute flowerless plants, so that through the 

 studies of Presl, Milde, the Hookers and others on ferns and 

 their allies, of Schimper, Leitgeb and others on mosses and 

 liverworts, of Agardh, Kuetzing, Harvey, Thuret and Bornet 

 on algae, of Fries, Persoon, and the Tulasnes on fungi, and 

 of Acharius and Nylander on lichens, the proportion of cryp- 

 togams to flowering plants gradually advanced, notwithstand- 

 ing a very great increase in the latter, until at about the close 

 of the third quarter of the century approximately one-fourth 

 of the 125,000 species then known were cryptograms. Then 

 came a much increased activity in the study of these minuter 

 plants, partly from the concentration on them of study no 

 longer believed to be necessary for the flowering plants of the 

 more accessible parts of the world, these having been fairly 

 satisfactorily disposed of on the grosser or so-called Linnaean 

 ideas of specific limitation, and partly because of DeBary's 

 studies of parasitism and a recognition that many of the 

 diseases of cultivated plants are caused by fungi, the differ- 

 entiation of which then became important from an economic 

 as well as a systematic point of view. At the close of the 

 century not far from 180,000 species of< plants were known, 

 of which some 75,000, or more than the total number of 

 species known in all groups at the end of the first quarter of 

 the century, are cryptogams. The last decade, however, has 

 witnessed a proportionally greater increase in phanerogamic 



