.5S 



OONFERVA BOMBYCINA. 

 By the Rev. W. W. Spicer, M.A., r.R.A.S. 



[Bead 10th April, 1877.] 



The Confervacese form a section of the great family of the 

 Algse, better known to us as sea weeds, although a large pro- 

 portion of them inhabit fresh and brackish water, as well as 

 the ocean. None of the Algae are highly constituted, con- 

 sisting as they do purely of cellular matter without a trace of 

 vascular tissue. In fact they stand at the very bottom of 

 nature's ladder ; varying, however, greatly in point of size 

 from the microscopic speck to the huge Gulf weed, whose 

 tangle branches reach for hundreds of feet in extent. 



Smallest of all plants probably, and simplest in its organi- 

 sation is Frotococcus nivalis, which, however, makes up for its 

 minuteness by the marvellous abundance of the individual 

 plants, and is well known to voyagers in the extreme North 

 under the name of Eed Snow. The red snow in fact con- 

 sisting of snow% whose surface is covered for miles with this 

 almost infinitesimally minute Algae. Each plant is composed 

 of a single cell, which multiplies by division, each new cell 

 separates, and again divides into other cells, the division (be 

 it observed), always occurring in multiples oifour. As this 

 process takes place with extreme rapidity (under favourable 

 circumstances) the surface of the snow is speedily stained by 

 these tiny organisms with a rich crimson hue. 



Another form of these lowly organised plants is common 

 enough in the old country, where it shows itself on gravel 

 paths, and like hard rough soils, as a lightish brown 

 amorphous mass, not unlike a lump of olive coloured jelly 

 This only occurs after rain, in dry weather the plant shrinks, 

 up and occupies so small a space as to be quite invisible. 

 The Algae indicated is a species of Nostoc, and when examined 

 under the microscope it proves to be composed of an infinite 

 number of filaments ; each filament being moniliform, or 

 having the appearance of numerous beads attached to each 

 other in a regular series — the system of filaments being 

 enveloped in a gelatinous pellicle. Nostoc, like most of the 

 lower Algae, propagates by division, the filaments breaking up 

 into separate parts, and each part becoming the nucleus of a 

 new mass of gelatine. 



Nearly allied to these are to widely dispersed groups, well 

 known to microscopists under the names of Desmids or 

 Diatoms. These consist of infinitely minute unicellular algae 

 which are as varied in form as they are abundant in 

 individuals. Scarcely a drop of standing water can be 

 examined without a specimen being found, and the muddy 



