182 



PROTOPHYTES. 



PART II. 



The slime that covers damp walls or stones, and moist 

 cliffs or rocks in the sea, also the slime or mucus that 

 sometimes swims on the surface of water, are said by M. 

 Bory de St. Vincent to be provisional creations waiting 

 to be organized. Of this the conferva, Palmogloea macro- 

 cocca (fig. 6), is an example. It is a green slime covering 

 damp places, consisting of microscopic primordial cells, 

 each of which is surrounded by a gelatinous envelope, 

 and filled with green granular matter occasionally con- 



Fig. 6. Palmogloea macrococca : A, full grown cell ; B E, successive stages of binary 

 division ; P, row of cells produced by a succession of subdivisions ; G i, cells treated 

 by iodine ; K M, cells in conjugation. 



centrated into a nucleus. This singular plant is pro- 

 pagated in two different ways. The endochrome or green 

 matter within the cell spontaneously divides into two 

 equal parts, the thin coat of the cell bends round the 

 two ends, separates them, then each half takes a globular 

 or ovoid form, and secretes a gelatinous substance round 

 itself which completes the separation, so that they form 

 two distinct and independent plants, in every respect 

 similar to that from whence they were derived. After 

 a little time, each of these plants undergoes a similar 

 bisection, so that four new plants are formed with their 



