20 INDEPENDENCE OF FIBRE. [BOOK i. 



The part of the Rhamni in which these loose vermicular 

 spirals were observed are certain obovate bodies belonging to 

 the nascent stipules of the leaf-buds. 



The frequent occurrence of such a structure in very young 

 organs, the loose fibres found in the hairs of the seeds of 

 Collomia, and other plants, in the elaters of Marchantia and 

 elsewhere, would seem to render the independent nature of 

 the elementary fibre unquestionable, notwithstanding its 

 more frequent adhesion to the inside of some cell or tube in 

 which it is generated. Nevertheless Mohl says (Botanische 

 zeitung, vol. xxii. p. 676,) " No doubt can be entertained by 

 any one, who has investigated the development of the spiral 

 fibres and the spiral cells, and who has recognised the decided 

 analogy between these two formations and dotted cells, 

 that the fibre of the spiral vessels is no peculiar formation, 

 existing by itself, but that it must be considered as the 

 secondary membrane of the vascular sac, having a spiral 

 direction, and divided into one or several parallel bands." 

 But I agree with Link in asking whether the membrane was 

 connected with the fibre at the moment of its first formation, 

 or whether a separation into fibres only takes place subse- 

 quently ? " I shall demand proofs if this question is answered 

 in the affirmative; and if in the negative if the fibre is 

 assumed to be separated from the membrane immediately at 

 its first formation I shall then ask further, What difference 

 is there in saying, the fibre is a peculiar independent tissue ; 

 or, a membrane is peculiar, and primitively separated into 

 fibres? The word 'depositing' does not explain anything; 

 on the contrary, it has the improbable unproved meaning, 

 that the formation of the fibre and of the membrane was a 

 mere act of precipitation. Even when fibre is pressed rather 

 flat, it has no similarity with the parts of a membrane ; for, 

 on magnifying 1500 times tissue from very young roots, 

 the tender fibres of the spiral vessels may distinctly be seen 

 rounded on the edges. The inclosing external membrane at 

 that period being so tender, that it cannot be perceived, I 

 should like to reverse the matter and to say, Whoever inves- 

 tigates the development of spiral vessels and of spiral cells, 



