322 VEGETABLE ORGANOGRAPHY. 



The external part is frequently distinct from the rest 

 of the tissue, and can be separated like a skin or bark 

 with little or no tearing ; it frequently bears true hairs 

 or scales produced by the fragments of pelKcles partly 

 detached. 



As to the general forms of Fungi, the little that I can 

 say is so intimately connected with the reproductive 

 organs, that I must refer the reader to the following 

 Book. 



Section VI. 

 Of the Algce. 



Of all the families of the class Cellulares, there is 

 none where the general character can be more easily 

 comprehended than these ; the usual transparency of 

 their tissue renders their observation very easy, and their 

 constantly living in water allows them to be observed 

 under the microscope in their natural state. 



The Alga9 are expansions, sometimes filiform, at others 

 foliaceous ; sometimes a mixture of these two states, but 

 of an absolutely homogeneous nature : their surface 

 never presents stomata, and as it exhales oxygen by the 

 action of light in the same manner as other plants, we 

 must conclude that these organs do not serve for that 

 purpose. The tissue of the Algae is entirely formed of 

 closed cellules, sometimes round, constituting the foli- 

 aceous limbs, — at others more or less elongated, forming 

 the appearance of stems, roots, or nerves. Several of 

 them present, in the interior of their tissue, spaces or 

 air cavities ; these are very visible in Chara. 



I 



