THE HIGHEll CRYPTOGAMIA. 243 



between the two is arrived at, if the difference between 

 hairs and leaves is sought for in the facts that the youngest 

 hairs are never seen below the first visible rudiments of the 

 leaves, and that leaf-formation on the axis always precedes 

 the formation of hairs. By trusting to these characters the 

 observer will never be in doubt, in any case where the axis 

 of the plant exhibits both these forms of appendicular 

 organs. The scales of ferns therefore, as well as the hairs in 

 the buds of mosses and liverworts, fall under the definition 

 of hairs, and the fronds consequently under that of leaves.* 



The formation of a frond commences thus — one of the 

 superficial cells of the terminal bud, distant from the next 

 older frond by the angle of divergence of the frond- arrange- 

 ment increases in size, and becomes arched outwards in a 

 papillate manner (PI. XXVII, fig. 4; PL XXXII, fig. 4), 

 In this cell there commences a series of divisions which are 

 repeated continually in the apical cell by means of septa 

 turned to the right and left towards the future margins 

 of the frond. The secondary cells multiply in all three 

 directions more vigorously on the hind surface of the 

 frond, so that the latter is converted into a somewhat 

 slender cone bent over towards the fore part. Septa are 

 now produced in the apical cell, turned towards the fore 

 and hind surfaces of the frond, and alternating with others 

 turned towards the lateral margins. The further formation 

 of the frond, the development of its blade, takes place in 

 the manner pointed out in Pteris aquilina. 



In the mature plant of Aspidium filix-mas roots (as we 

 have already said) are no longer formed on the stem itself, 

 but exclusively on the protuberant swollen portion of the 



* Two of the main grounds formerly adduced to prove that the scales were 

 of the nature of leaves, and the fronds of the nature of branches, have been 

 set aside. Kunze's statement, that the delicate bodies, resembling the fronds 

 of Trichomanes, found at the base of the stipes of Hemitelia capensis are 

 transformed scales, is erroneous, as has been already observed. They have 

 nothing in common with scales as may be seen at once by the examination 

 even of a dead stem. The course of the vascular bundle within them is con- 

 clusive to show that they have been formed in the earliest stage of the frond, 

 even before the commencement of the formation of the blade of the latter. I 

 have latterly arrived at a very clear view of the growth in the Ophioglossese. I 

 formerly thought that it must be considered to consist of a successive series of 

 adventitious buds. I now find that the Ophioglosseae agree essentially with the 

 Polypodiacese. 



