THE HIGHER CRYPTOGAMIA. 147 



be formed, nothing more seems necessary for its production 

 than that green colouring matter should be formed in a 

 cell, and should enter into combination with a mass of pro- 

 teine substance. The investigations of Arthur Gris (' Ann. 

 des Sc. Nat.,' iv ser., t. vii, p. 79), and of Sachs (' Sitznngs- 

 berichte Wiener Akademie,' xxxvii, (1859,) p. 108), have 

 since shown that even in higher plants the chlorophyll- 

 granules are formed by the disruption of a sharply-defined 

 mass of protoplasm, often of no determinate shape, the 

 green colour of which in certain cases becomes apparent 

 before the disruption, in others during that process, and in 

 others again after the disruption, and which mass of proto- 

 plasm is usually agglomerated round the nucleus. 



The development of the leaves of mosses has lately been 

 a matter of discussion. Nageli asserted that the leaf 

 grows exclusively at the apex and the edge. (' Zeitschr. 

 fiir wiss., Bot.' ii, 175). Schleiden, on the other hand 

 (Grundziige, 3 Aufl), advanced a diametrically opposite 

 opinion. According to him the leaf is pushed forwards by 

 the multiplication of cells lying inside the circumference 

 of the stem ; the apex of the leaf being the oldest, and 

 its base the youngest portion. With regard to the moss 

 which Schleiden examined, viz., Sphagnum, this is abso- 

 lutely incorrect; with regard to the leaves of liverworts 

 and phcenogams it is only true in part, and to a very 

 limited extent. Both observers have generalised too ex- 

 tensively from the results they have obtained in their 

 investigations of mosses, although INageli subsequently 

 limited his too vague conclusions, by acknowledging the 

 frequent occurrence of intercalary cell-multiplication,* a 

 very manifest fact long previously pointed out by Grisebach 

 (' Wiegm. Arch.' 1846, p. 1). I have before attempted 

 to show that, with regard to mosses, the truth lies 

 between the two opinions. The first rudiment of the leaf 

 is formed from an outwardly-protruding cell of the circum- 

 ference of the terminal bud, by means of continually 

 repeated division of the apical portion. In this rudiment 



* Nageli called this " accidental cell-formation" an expression the incorrect- 

 ness of which he subsequently acknowledged, 'PfLanzen physiol. Unters.,' 

 i, p. 83. 



