STRUCTURE.] FORMS OF TISSUE. 21 



must acknowledge the fibre to be a peculiar independent for- 

 mation." (See Link's Report upon the Botany of 1841, as 

 translated for the Royal Society by Dr. Lankester.) 



Of the organic mucus, membrane, and elementary fibre 

 thus described, all the elementary organs of plants are con- 

 structed. For the convenience of description, they may be 

 considered as of five different kinds, 1. Cellular tissue, or 

 Parenchym ; 2. Pitted tissue, or Bothrenchym; 3. Woody 

 tissue, or Pkurenchym ; 4. Vascular tissue, or Trachenchym ; 



5. Laticiferous tissue, or Cinenchym* 



There is no doubt that all these forms are in reality modi- 

 fications of one common type, namely, the simple cell, how- 

 ever different they may be from each other in station, function, 

 or appearance. For, in the first place, we find them all 



* Professor Morren has proposed the following nomenclature of tissue, which 

 has some advantages over that more commonly in use. I. PARENCHYMA ; 



I. merenchyma,orsphcerenchyma, spherical ; 2. conenchyma, conical, as in hairs ; 

 3. ovenchyma, oval ; 4. atractenchyma, fusiform ; 5. cylindrenchyma, cylindrical ; 



6. colpenchyma, sinuous; 7. dadenchyma, branched; 8.p*zsme7tc/tyma,prismatical. 



II. PERENCHYMA, amylaceous granules. III. INENCHYMA, fibro-cellular tissue. 

 IV. ANGIENCHYMA, vascular tissue ; 1. pleurenchyma, woody tissue ; 2. trachen- 

 chyma, spiral vessels ; 3. modified trachenchyma, ducts ; 4. cinenchyma, laticife- 

 rous vessels. Count de Tristan distinguishes tissue into several kinds. Common 

 spheroidal tissue is for him aphrostase, because it resembles foam. Prismatical 

 cellular tissue is hegemon, A division, or fissure, which he calls " cwnice" 

 separates, in trees, the bark from the internal part, or " endophyte " as he terms 

 it The inner part, however, does not consist of a single part, but of the pith, 

 and that which is called wood, but which does not always deserve this name, as 

 it is frequently very soft in herbs. Count de Tristan therefore terms it " endos- 

 tere" because it is at all events firmer than the surrounding part. As to the 

 so-termed " prolongemens medullaires," he says that they originate from the 

 " tissue aphrostasien," that they continually get smaller, and that the vascular 

 bundles which have grown up, thicken, at last only leaving a trace of them. He 

 therefore terms them " isthmes aphrostasiens" or briefly " isthmes" The con- 

 sideration of a transverse section in the stem of a bramble (Rubus fruticosus) 

 leads him to the adoption of a third tissue, which he terms "proxyle," distin- 

 guishing it by the circumstance, that it consists of prismatic or cylindrical fibres 

 (filets) of an indefinite length ; this is the woody tissue of liber. He examines 

 it from its first origin, and finds that it also consists at first of cambium, so 

 that each of the three tissues has its own peculiar cambium. These tissues are 

 very often intermixed, and he terms such a mixture, which is produced from 

 an effusion of the "proxylaire " cambium, into another already formed tissue, an 

 " addonie" (Link's Report). 



