570 APPENDIX. 



Page 38., add to History and Criticism. 



In conclusion, I give an as complete as possible review of the whole 

 history of the study of vegetable cell-formation since 1838, in which 

 year, through my work, the origin of the vegetable cell was first declared 

 to be the fundamental problem in Botany. 



A dissertation on the multiplication of the vegetable cell by division, 

 by Hugo von Mohl, had indeed appeared earlier, in 1835, but this only 

 bore reference to one isolated case, and a more recent revision of it will 

 be mentioned below. In other cases, I place the researches in chrono- 

 logical order. I restrict myself to a brief statement of the peculiar 

 observations and opinions of the authors, without entering upon a criti- 

 cism of them, or the refutations which they have received one from 

 another. Only I must mention that I do not go minutely into Hartig's 

 views (Das Leben der Pflanzenzelle, Berlin, 1844), because, as Mohl has 

 already remarked, he has such a very different way of looking at the 

 things from us, that it is impossible to give an account of the matter 

 without using his own words, and at equal length with himself. 



1838. Schleiden, Beitrage zur Phytogenesis, in Miiller's Archiv 

 (Beitriige zur Botanik, p. 129.), The contents have been given at 

 length above. 



Unger, Aphorismen zur Anatomic u. Physiologic der Pflanzen. 

 Vienna, 1838. Here we find a resurrection of Grew's opinion, that 

 the cells originate as cavities in homogeneous mucilage, without inde- 

 pendent walls. This appears to me rather speculation than observa- 

 tion. 



Hugo von Mohl, On the Development of the Stomates, in the Linna3a, 

 1838 (Vermischte Schriften, p. 252.). An instance of multiplication of 

 cells by the so-called division. 



1839. H. v. Mohl, Development of the Spores of Anchoceros Icevis, in 

 the Linnaea, 1839 (Vermischte Schriften, p. 84.), relates the origin of 

 transparent utricles in the mucilaginous contents of the cells, whereby the 

 nitrogenous lining (primordial utricle) is gradually detached from the cell- 

 contents, and at the same time, by the meeting of the utricles, becomes 

 defined at the points of junction of the course of the little mucilage 

 currents in cells. The nucleus of the parent-cell is persistent, and 

 another is formed, which, by repeated division, multiplies to four, which 

 arrange themselves tetrahedrally. Septa then divide the parent-cell 

 into four parts, in such a manner that the nuclei lie in the middle of 

 each subdivision. At the same time the nucleus of the parent-cell dis- 

 appears. The four newly-formed cells subsequently separate, with 

 special walls, from the parent-cell, lie free in it, and finally are emitted 

 by the destruction of the parent-cell. 



1840. Schleiden, Zur Anatomie der Cacteen (Mem. de 1'Acad. de St. 

 Petersbourg, 6th series.) The contents have been incorporated above. 



1841. Unger, in the Linnaea. The nuclei are formed subsequently 

 in the completed cell. 



1842. Ndgeli, Ueber Entwicklung des Pollens; Zurich. Describes the 

 development of the cell around a central nucleus in the pollen granules 

 of the Phanerogamia. 



Ncigeli, in the Linnaea. Development of the cells of the stomates. A 

 small triangular mark between the two secondary cells, which have 



