82 GELATINOUS, CRUSTACEOUS, AND STONE-LIKE ALGiE. 



CHAPTER IX. 



OF THE GELATINOUS, CRUSTACEOUS, AND STONE-LIKE ALG^E. 



We find among the Algae a considerable group in which, 

 the external membrane possesses the peculiar property of 

 surrounding itself with a gelatinous substance, varying in 

 its consistency in the different species : and in this mucous 

 matter the inner cell (or Gonidium of Kiitzing) lies em- 

 bedded. As the cells continue to multiply, colonies are 

 raised (larger or smaller according to the amount of division 

 in the original ceil), forming masses which are generally 

 amorphous, though sometimes of a definite outline, and 

 then usually spherical. In this way arise the soft gelati- 

 nous layers of a portion of the Rivulariaceas and Chasto- 

 phoracese, a kind of slimy matter holding together the indi- 

 vidual filaments. 



Such species may be looked for in marshy stagnant 

 pieces of water, on damp earth and the surface of wet 

 rocks, where they form a smooth jelly-like coating. The 

 species found in water usually commence their existence 

 on stones or attached to water-plants, from which they 

 eventually separate themselves and then float on the 

 surface. When this is the case, they are to be collected by 

 means of the ' tea-sieve,' and from thence transferred to 

 a wide-mouthed bottle ; while those that are adherent 

 must be taken up together with the object on which they 

 rest. If growing on rocks, they may be scraped off. No 

 special preparation is needed. The gelatinous substance 

 may be divided into any convenient number of portions, 

 and dried upon paper. When thoroughly damped at a 

 future period, the masses will swell out to very nearly 



