KARL WILHELM VON NAEGELI. 379 



(1861) his accuracy as an observer is shown, for in this paper he 

 first figured correctly the young female condition of ilio' Floridece, 

 but again failed to comprehend the true significance of his obser- 

 vation, and it was left to Bornet and Thuret, in 1867, to give the 

 proper explanation and fix the true position of the Floridece. It 

 may be said that had Naegeli studied living instead of alcoholic 

 material, he might perhaps have avoided his error. Naegcli's 

 paper on the cell division in Delesserla Ili/jjoglossum and on the 

 structure of Caulerpa proUfera were also valuable contributions to 

 our knowledge of algse, and his " Gattungen einzelliger Algen " 

 (1849), more purely systematic than his other works on algye, still 

 remains a classic monograph on the subject. 



In his first histological paper (1841) on the development of pol- 

 len, and in later papers on the development of stomata and the 

 structure of the root-apex, Naegeli proved himself to be a better 

 observer than his teacher, Schleiden, and in two important papers 

 published in 1844 and 1846 on nuclei and the formation and growth 

 of vegetable cells, he showed emphatically that cell division is the 

 true mode of vegetative cell formation. Although in his earlier 

 paper on the growth of the leaf, Naegeli had been led to errone- 

 ous views on the nature of stems and leaves, nothing but praise 

 can be said of his paper on the ''Growth of the Stem and Root in 

 Vascular Plants and the Arrangement of the Vascular Bundles " 

 (1858). This paper is regarded by botanists as his most important 

 histological work, and is the basis of the countless works of more 

 recent writers on the subject. The enormous work of over six 

 hundred pages on starch grains (1858) is full of important obser- 

 vations, and served as the foundation of the micellar theory, which 

 has been alternately attacked and defended up to the present time, 

 one phase of the discussion being the method of formation of cell 

 walls by intussusception as opposed to apposition. For some time 

 the preponderance of opinion rather favored Naegeli 's theory of 

 intussusception, but, although the question cannot as yet be said 

 to be settled fully, the advocates of the theory of apposition have 

 of late appeared to have the strongest evidence on their side, and 

 physicists, as a rule, do not regard the micellar theory with much 

 favor. 



Naegeli's writings on fermentation, ''Theorie der Gahrung " 

 (1879), with which may be classed properly his "Die niederen 

 Pilze " (1877), represent rather his theoretical views based on 

 the work of others than conclusions founded on his own work. 



