TYPES OF CRYPTOGAMS; THALLOPHYTES 253 



THE STUDY OF NEMALION 



296. Occurrence. Seven or eight species of Nemalion are known 

 in the world, but only one l is widely diffused, being found in Europe 

 and on the New England coast from Rhode Island northward. It 

 grows in salt water attached to exposed rocks at low-water mark. 

 Nemalion represents the largest of the groups of algse, nearly all of 

 which live in salt water and have the characteristic color ; but a few 

 live in fresh water. 



297. Color. Fresh specimens or those properly dried for the 

 herbarium show the color which is characteristic of the great group 

 to which Nemalion belongs. Dried specimens of " Irish moss " 

 (Chondrus) and many other species furnish good illustrations. There 

 are many variations of shade and intensity. 



Place a piece of a fresh or dried specimen of some species in a 

 beaker of fresh water over night or longer and note the color of the 

 solution and of the treated specimen. Treat another piece similarly 

 with alcohol. A few genera related to Nemalion grow in fresh 

 water. What do you infer regarding their color ? 



298. Form and General Character. Examine specimens of 

 Nemalion and note the size, shape, mode of branching, nature, or 

 consistency of their substance. Examine a fragment of the plant 

 with a power of about sixty diameters and note how the structure 

 differs from what it appears to be to the naked eye. Do cells appear 

 more densely packed or differently colored at any points? 



299. Structure. From a small portion of the plant cut thin 

 longitudinal and transverse sections or pull it to pieces with needles 

 so as to expose the inner portion. Place on a slide under a cover- 

 glass in a drop of water. With a power of about 250 diameters or 

 more examine the general structure of the frond, as shown by a slide 

 prepared as above. Note the central portion (axis') of the frond as 

 dissected out, consisting of long, slender, thread-like cells. Examine 

 and draw the branching rows of cells which, radiating from the 

 axis, form the surrounding outer structure of the frond. Note the 

 tips of .these branches and look for the fruiting organs and fruit 

 (spores). 



