82 GELATINOUS, CRUSTACEOUS, AND STONE-LIKE ALGAL 
CHAPTER IX. 
OF THE GELATINOUS, CRUSTACEOUS, AND STONE -LIKE ALGA). 
We find among the Algse 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 cell), 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 Cha3to- 
phoraceaa, 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 
