78 FABRIC OF PLANTS. 



Grew seems to have held a somewhat different 

 opinion, and describes it as a separate membrane com- 

 posed of minute cells, or, as he terms them, "blad- 

 ders," which shrink and are dried up as the plant 

 grows older. 



Du Hamel denies the existence of the cells described 

 by Grew, and says the rind is composed of fibres across 

 the trunk, and that these in the birch are connected 

 with other lateral fibres. 



Comparetti also describes it as formed of fibres, in- 

 terwoven with six- sided meshes, with vesicles between 

 filled with air. 



Desfontaines says it resembles thin parchment, with 

 numerous pores extremely minute. 



Kieser, who studied the rind with great care, comes 

 nearly to the same conclusion as Grew. In a species 

 of fern, he found a network of vessels by which the 

 rind, as he thinks, is formed. 



Krocker again thinks Kieser was mistaken, his sup- 

 posed net- work vessels being nothing more, he says, 

 than the sides of the cells beneath ; and Krocker is 

 supported in this by Jurine, Mirbel, Sprengel, and 

 Link. 



Saussure, the elder, describes the rind as formed of 

 a very thin outer skin, full of very minute pores, and 

 beneath it a very delicate net- work of vessels. 



Bauer describes the rind as cellular, and as varying 

 considerably in different species of plants. 



De Candclle describes the rind to be in certain parts 

 a simple membrane, and in other parts to be formed 

 of layers, composed of cells. In the young state it is 



