PLANT MORPHOLOGY 67 



leaf existed from the first, and was in fact the predominant part in 

 the initial composition of the shoot, has been held by certain, writers 

 as the basis of origin of the leafy shoot in vascular plants. 1 On this 

 view not only is the whole shoot regarded as being mainly composed 

 of leaves, but some even contend that the axis has no real existence 

 as a part distinct from the leaf-bases. 2 The way in which this is 

 pictured as having come about is by branching of a sporogonium of a 

 bryophyte: the sporogonial head of one limb of such a branching 

 became vegetative as the first leaf, while the other continued its 

 growth, and branched again: thus the apex of the first lateral 

 appendage was of the nature of a sporogonial head: this condition 

 has been compared with that seen in the embryo of a fern, or of 

 some monocotyledons. 3 



This view in its general form represented the plant as constructed 

 on a plan somewhat similar to that of a complex zoophyte. It has 

 more recently culminated in the writings of Celakovsky and Delpino. 

 The former in his theory of shoot-segments (Sprossgliedlehre) starts 

 from the position that the plant is composed of morphological 

 individuals: the cell, the shoot, and the plant-stock are recognized 

 as such. The stock is composed of shoots, and the shoot of cells. Braun 

 recognized the shoot as the individual par excellence: between the cell 

 and the shoot is a great gulf, which has not yet been filled : " between 

 the cell and the bud (shoot) there must be intermediate steps, the 

 limitation of which no one has succeeded in defining:" the long- 

 sought-for individual middle step is the shoot-segment (Spross- 

 glied), which is neither leaf only, nor stem-segment only, but the 

 leaf together with its stem-segment. Now this appears to me to be 

 purely Platonic morphology: the intermediate step must occur; 

 we will therefore discover and define it. The definition of it con- 

 sists fc in the drawing of certain transverse and longitudinal lines 

 partitioning the shoot, lines which in the sporophyte have no existence 

 in nature: the assumed necessity of partitioning the shoot into 

 parts of an intermediate category between the whole shoot and the 

 cell brings these assumed limits into existence. 



In support of his theory of shoot-segmentation, Celakovsky (loc cit. 

 p. 101) adduced evidence from the development of the embryos 

 of certain monocotyledons; from certain inflorescences; from the 

 origin of the leafy moss stem on the protonema; and from the 

 actual existence of the leaf-forming segments in mosses and pterido- 



1 Goethe, Die Metamorphose der Pflanzen. Gaudichaud, Memoire de I' Academic 

 de Science, 1841. Kienitz Gerloff, Botanische Zeitung, 1875, p. 55. Celakovsky, 

 Unters. uber die Homologien, Pringsh. Jahrbuch, xiv, p. 321, 1884. Botanische 

 Zeitung, 1901, Heft v, vi. 



2 Delpino, Teoria generate della Filotassi. For reference see Bot. Jahresbr., vin 

 (1880), p. 118, also vol. xi (1883), p. 550. 



3 Celakovsky, loc. cit. Kienitz Gerloff, loc. cit., compared the first leaf with half 

 of the sporogonial head, in the case primarily of fern embryos. 



