ALG.E 5 



of vinegar, the tanning of hides, the ripening of cheese and the retting 

 of flax. 



To-day the study of Bacteriology as an applied science is becoming 

 so broad that it consists of several special branches, the most impor- 

 tant of which are Bacteriology in relation to Disease of Animals and 

 Plants, Dairy Bacteriology, Soil Bacteriology, Bacteriology in relation 

 to Water Supply and Sewage Disposal, and Household Bacteriology. 



ALGM 



Nearly all of the Algae which are of any economic importance are 

 included in the marine forms collectively known as seaweeds. Of the 

 four principal groups only two, namely, the brown algse (Phseophyceae) 

 and red algse (Rhodophycese), yield commercial products. On 

 account of their large yield of mucilage quite a number are used 

 locally for food purposes. The ash of a number of the kelps, as Fucus, 

 Laminaria, etc., still continue to be the source of iodin. A few of the 

 kelps have been used in phthisis, their value no doubt being due to 

 the iodin content. 



LAMINARIA. Devil's Apron. The cylindrical stipes and basal 

 portions of the midribs of the fronds of Laminaria digitata and L. 

 Clustoni (Fam. Laminariaceae). The former is a very characteristic 

 kelp which is common north of Cape Cod. The fronds are attached 

 to the rocks by fibers which are frequently arranged in whorls and 

 from which arise a stout and solid stipe, from 3 to 15 dm. in length 

 and which is more or less cylindrical below, compressed above and 

 free from distinct mucilaginous cavities (muciparous glands). When 

 well developed the stipe projects rigidly above the surface of the 

 water at low tide and from which extends the oval or lanceolate 

 lamina, which at the summit is split into digitate segments varying 

 from 6 to 18 dm. in length and 3 to 9 dm. in width. L. Clustoni is a 

 common European form and resembles L. digitata. In the prepara- 

 tion of the commercial article the stipes and lower portion of the 

 midribs are cut into pieces of convenient length and quickly dried. 

 They were formerly used in the manufacture of tents and bougies, 

 to which they were well adapted, owing to the fact that the cell walls 

 are mucilaginous, so that the stipes increase six-fold upon the absorp- 

 tion of water from the parts to which they may be applied. As 

 they cannot be sterilized without losing this property, they have 

 been replaced by other materials. In a similar way a number of 

 other vegetable substances have been used. 



