LECT. III.J VASCULAR TEXTURE. 



the round pores of the last described 

 They are also surrounded by a border 

 (fig. /*), and convey resinous and oily 

 secretions. They are found in greatest 

 number in the less compact woody parts 

 of the plant. The centre of the majo- 

 rity of the species belonging to the family 

 of plants named Lycopodium contain a thick 

 cylinder, which is chiefly composed of vessels of 

 this kind. Ferns also inclose many of them, in 

 their woody threads ; and several other plants, 

 particularly the Vine, the wood of which is soft 

 and porous, contain them in great numbers. Mirbel 

 denominates them les fausses trache*es; but as 

 the analogy by which they are thus named is not 

 just, I conceive we are more correct in calling 

 them, from their structure, ANNULAR OR RINGED 

 VESSELS. 



Each of these species of perforated vessels is 

 occasionally seen forming different parts of the 

 same tube ; or one portion of it may present the 

 cribriform characters, and another the annular. 



3. The next set of vessels, the SPIRAL, has been 

 known to Botanists since the, time of Grew, who 

 was the first that gave his attention to the ana- 

 tomy of plants. They have been named vasa spi- 

 ralia, andjissurce spirales, from their appearance ; 

 and trachea? from their resembling the tracheae of 

 insects, and from an unfounded opinion that 



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