VEGETABLE ORGANIZATION. 59 



several classes of cells, and dignified by separate 

 technical denominations, which I shall not stop to 

 specify, as it does not appear that they have as yet 

 thrown any light on vegetable physiology. 



The chemical composition of the vegetable tissue, 

 composing these primitive cells and tnbes, appears 

 to be identical with starch, or fecula. Like starch, 

 it is rendered blue by the action of iodine ; and it 

 possesses the same optical property of giving to the 

 rays of polarized light which traverse it a circular 

 rotation directed towards the right : it contains no 

 nitrogen. This primitive vegetable membrane pre- 

 sents universally the same composition and proper- 

 ties throughout the vegetable kingdom ; whether 

 examined in the lower orders of Fungi and Algae, 

 or in the higher class of plants.* 



Many of the cells are fortified by the addition of 

 elastic threads, generally disposed in a spiral course, 

 and adhering to the inner surfaces of the membra- 

 nous coats of the cells, which they keep in an 

 expanded state. (See Fig. 9.) When the mem- 

 branes are torn, the fibres, being detached, unroll 

 themselves, and being loosely scattered among the 

 neighbouring cells, give the appearance of fibrous 

 connexions among these cells, which did not origi- 

 nally exist. Simple membranous cells, containing 

 no internal threads, are often found intermixed with 

 these fibrous cells. In many of the cells, again, 

 the original spiral threads appear to have coalesced 

 by their edges; thus presenting a more uniform 

 surface, excepting that a few interstices are left, 

 where the pellucid membrane, having no internal 

 lining, presents the appearance of transverse fissures 



* See Payen, Ann. Sc. Nnt. serie 2, xi, 21. 



