CHAP.V.] the Influence of the Knowledge of Cryptogams. 197 



results it was established by these facts, that morphological 

 differentiation during growth must not be regarded as an effect 

 of cell-divisions, and from such cases as these the conception 

 of the cell experienced a notable expansion. 



Moreover, Nageli was not satisfied with seeking instructive 

 examples for general morphological axioms in the lower Cryp- 

 togams ; he devoted special study to the Algae for systematic 

 and descriptive purposes ; and his ' Neuen Algensysteme,' 

 which appeared in 1847, and ' Gattungen einzelliger Algen,' 

 of 1849, were the fi rst successful attempts to substitute serious 

 investigation for the mere zeal of the collector in this part of 

 the vegetable kingdom, which had not indeed been hitherto 

 neglected, but had not been systematically worked since the 

 time of Vaucher. In the same spirit Alexander Braun also in 

 his ' Verjiingung ' contributed a rich material of new obser- 

 vations on the mode of life of the Algae and the morphological 

 conditions connected with it, and his labours were followed in 

 the succeeding years by the important researches of Thuret, 

 Pringsheim, De Bary, and others, to which we shall recur in a 

 later portion of this history. 



But before the examination of the Algae, and soon after of 

 the Fungi also, led to such great results, the systematic botany 

 of the higher plants underwent important changes through the 

 methodical study of the embryology of the Muscineae and Vas- 

 cular Cryptogams. These groups had been frequently and 

 carefully examined by good observers since the last century, 

 and the systematists, without penetrating deeply into the 

 peculiarities of their organisation, had brought the species and 

 genera, the families and even the higher divisions into tolerable 

 order. Comprehensive and methodically arranged catalogues 

 of these plants had been formed, and attempts had been made 

 to explain their morphology by that of the Phanerogams ; 

 Schmidel 1 published valuable observations on the Liverworts 



1 Casimir Christoph Schmidel was born in 1718 and died in 1792; he was 



