xxxm 



the form of male organs (antheridia) and female organs, "in which, 

 as a mle, four spores are developed." For several years Nageli con- 

 tinued to hold the view that the mother-cells of the tetraspores are 

 the female organs of the Florideee ; thus, in his paper, " Beitrage zur 

 Morphologie und Systematik der Ceramiaceas" (' Sitz.-ber. d. k. B. 

 Akad. d. Wiss.,' 1861; also * Bot. Mittheii.'), he says, with reference 

 to this view, that up to that time he had seen no sufficient reason for 

 changing it. And yet, in this very paper, he gives an excellent 

 description, with good figures, of the development of the " Keim- 

 frucht " of Callithamnion, an organ which, but a few years later 

 (' Mem. de la Soc. des Sci. Nat. de Cherbourg,' vol. 12, 1865 ; ' Ann. d. 

 Sci. Nat., Botanique,' ser. 5, vol. 7, 1867) Bornet and Thuret proved, 

 by observing the process of fertilisation, to be the true female organ 

 (procarp) . 



The discovery in the Algse of the growing-point with an apical cell 

 was probably the inducement which led Nageli to study the growing- 

 point in other groups of plants. He first described the apical cell 

 and the mode of growth of the stem in various Mosses and Liver- 

 worts (' Zeitschr.. f. wiss. Bot.,' Heft 2), and subsequently ("Ueber 

 das Wachsthum des Gefassstammes," loc. cit., Heft 3 and 4), 

 he discovered that in Lycopodium and in Monocotyledons and Di- 

 cotyledons, the growing-point of the stem has no apical cell, but 

 consists of a small-celled merismatic tissue, in which he traced the 

 first indications of the differentiation of the permanent tissues. 

 From this he went on to the fundamental anatomical work which 

 constitutes the main portion of the ' Beitrage zur wiss. Botanik,' in the 

 form of three papers : (1) "Das Wachsthum des Stammes und der 

 Wurzel bei den Gefasspflanzen, und die Anordnung der Gefassstrange 

 im Stengel " (Heftl, 1858) ; (2) " Dickenwachsthum des Stengels und 

 Anordnung der Gefassstrange bei den Sapindaceen "; and (3), in 

 conjunction with Leitgeb, " Entstehung und Wachsthum der Wiir- 

 zeln." The last of these papers was for years the authoritative work 

 on the anatomy and growth of the root : it is true that Hofmeister 

 (' Vergl. Unters.', 1851) had already discovered the fact that in 

 many of the Vascular Cryptogams the growth of the root is effected 

 by a single apical cell, but this detracts but little from the value of 

 Nageli's work. This paper also contains the recognition of the 

 morphological peculiarities of the " rhizophores " of Selaginella. 



The papers in the ' Pflanzenphysiologische Untersuchungen ' which 

 call for special notice are that on the " Primordialschlauch " (Heft 1 

 1855), and that on the " Starkekorner " (Heft 2, 1858). The chief 

 importance of the former is the light which it throws on the physics 

 of the cell, with special reference to the influence of the living ' prim- 

 ordial utricle " on diosmose. a subject which was also engaging the 

 attention of Pringsheim ('Bauund Bildung der Pflanzenzelle,' 1854), 



