ACROGENS. 



195 



193. Algacea or Alga. Leafless plants, with no distinct 

 axis ; growing in water, consisting either of simple vesicles, 

 or of articulated filaments, or of lobed fronds. Reproductive 

 matter either wanting or in the joints of the filaments, or 

 in thecse of various forms. Spores in germination elongating 

 in two opposite directions. 



USES. A nutritious gelatinous matter is obtained from 

 certain Gracilarias, and Chondrus crispus, sometimes called 

 Irish Moss. Gigartina Helminthochorton has been em- 

 ployed as an anthelmintic. They are generally collected 

 under the name of Wrack for burning for Kelp, formerly the 

 source of Carbonate of Soda. The substance sold in the 

 shops under the name of Laver is the Porphyra laciniata, 

 and vulgaris, and the Ulva latissima. 



TYPICAL GENERA. Fucus, Conferva. 



Reproductive organs of 320. Lawrencia pinnatifida. 321. Vaucheria geminata, 

 322. Dictyosiphon foeniculaceus. 323. Bonnemaisonia asparagoides. 324. Aspe- 

 rococcus echinatus. 325. Odonthalia dentata. 326. Lichina confinis. 327. Fucus 

 vesiculosus. All from Greville's Algae Britannic*. 



194. Fungacea or Fungi. Plants consisting of cellules, 

 among which filaments are occasionally intermixed, increas- 

 ing in size by addition to their inside ; their outside under- 

 going no change after its first formation, frequently ephemeral. 

 Spores lying either loose among the tissue, or enclosed in 



sporidia. 



o2 



