SECT. ii. PALMOGLCEA MACEOCOCCA. 183 



gelatinous envelopes; by the same process eight are 

 produced and so on indefinitely, the organ of nutrition 

 being the same with that of reproduction. Again, the 

 membrane or film that covers each of these primordial 

 cells is so thin and soft, that occasionally two adjacent 

 cells of the series unite into one mass by a fusion of 

 their sides and internal matter, which is then coated by 

 a membrane, and after various internal changes becomes 

 a spore which terminates a generation. By and by the 

 spore germinates, produces a green primordial cell 

 which secretes a gelatinous coat, and becomes by the 

 process of bisection the parent of a new generation, 

 which terminates by the union of two adjacent cells to 

 produce a spore, a cycle of alternate modes of reproduc- 

 tion that may be continued till ended by some external 

 circumstance, as the cold of winter. 



When the matter in two adjacent cells joins to form a 

 spore, it becomes granular, and mixed with minute par- 

 ticles of oil, which unite in a drop ; and the spore, which 

 is at first green, gradually assumes a yellow brown 

 colour ; conversely when the spore begins to grow, the 

 oil disappears, and the green matter takes its place. 

 This is a frequent occurrence during the formation of 

 spores in this class of plants, for the endochrome or 

 internal matter, which consists of a small variety of 

 elements probably in a state of unstable equilibrium or 

 change, is easily decomposed and recombined into new 

 substances by chemical action, but the bisection of the 

 cells of the Palmogloea so as to form new individuals is 

 probably owing to heat alone. There is no apparent 

 difference between the cells selected to produce spores 

 by their union, and the others. It seems that in every 

 plant certain cells are reserved for certain purposes. 

 Professor Karsten conceives the nucleated cells to be 

 reserved for reproduction, while those destitute of nuclei 

 are designed for secretion. 



