2io Morphology and Systematic Botany under [BOOK i. 



cineae ; it was shown that very different forms of sexuality and of 

 general development occur in the Algae, and these led to the 

 formation of systematic groups, quite different from those 

 founded on the superficial observation of collectors. It soon 

 appeared in the Algae, and later in the Fungi and Lichens, 

 that special investigation must lay new foundations for the 

 system. From the confused mass of forms not before under- 

 stood, Pringsheim brought out a series of characteristic groups, 

 which, thoroughly examined and skilfully described in words 

 and by figures, stood out as islands in the chaotic sea of still 

 unexamined forms, and threw light in many ways on all 

 around them. In like manner the morphology of the Con- 

 jugatae was thoroughly examined by De Bary before 1860; 

 fragments of the history of development in the Algae were 

 added by Thuret, and he and Bornet cleared up the remark- 

 able embryology of the Florideae in 1867, while Pringsheim 

 established the pairing of the swarm-spores in the Volvocineae 

 in 1869. The Algae offer at present a greater variety in the 

 processes of development than any other class of plants ; 

 sexual and asexual propagation and growth work one into the 

 other in a way which opens entirely new glimpses into the 

 nature of the vegetable world. 



The old conceptions of the nature of plants had been 

 greatly modified by Hofmeister's discovery of the alternation 

 of generations, and the reduction to it of the formation of the 

 seed in Phanerogams ; in like manner the first beginnings 

 of plant-life, the simplest forms of Algae, exhibit phenomena 

 which compel us to revise our fundamental conceptions of 

 morphology, if we are ever to be able to give a systematic view 

 of the whole vegetable kingdom. 



The methodical examination of the Fungi after 1850 led to 

 similar but still more comprehensive results. From earliest 

 times the Fungi had been objects of wonder and superstition ; 

 what Hieronymus Bock said of them has been told in the 

 first chapter ; this was repeated by Kaspar Bauhin, and similar 



