90 TENTH ANNUAL REPORT OE ♦ 



portions, and at the same time a cell-wall is .farmed between eacli por- 

 tion, and thus the original simple cell becomes two cells. These no 

 longer cohere together, as cells do in a compound plant, but each 

 hall-cell separates from its fellow, and commencing an independent 

 career, digests ibod, increases in size, divides at maturity, &c., going 

 again and again through a similar round of changes. In this way, 

 by the process of self-division, and without any fructification, a large 

 surface of water may soon be covered with tliese vegetable monads, 

 from the mere multiplication of a single individual. 



These minute plants, {Dlatomacece and Denmidiacexe) from their 

 microscopic size and uniform and simple structure, are justly regarded 

 as at the base of the vegetable kingdom. Notwithstanding which 

 lowly position in the scale of being, they display an infinite variety 

 of the most exquisite forms and finely sculptured surfaces ; so that 

 their study affords as much scope for the powers of observation as 

 does that of the creation which is patent to our ordinary senses. 

 These tribes are, however, omitted from this essay, because they have 

 been made the objects of special inquiry by Professor Bailey of AVest 

 Point, whose memoirs in the volumes of the Smithsonian Contribu- 

 tions are referred to for further information. 



But Dcsmidiacece and Dlatomacece are not the only Algro of this 

 simple structure. The lowest forms of the order FalmeUaceoi, such 

 as the Frotococcus or Red snoiv plant, have an equally simple organ- 

 ization. The blood-red color of Alpine or Arctic snow which has 

 been so often observed by voyagers, and v/hich was seen to spread over 

 so vast an extent of ground by Captain Pioss, in his first Arctic journey, 

 is due to more than one species of microscopic plant, and to some 

 minute infusorial animals which perhaps acquire the red color from 

 feeding on the Frotococcus among which they are found. ^ The best 

 known and most abundant plant of this snow vegetation is the Fro- 

 tococcus nivalis, which is a spherical cell, containing a carmine-red 

 globe of granulated, semi-fluid substance, surrounded by a hyaline 

 limbus or tliick cell-wall. At maturity the contained red matter 

 separates into several spherical portions, each of which becomes 

 clothed with a membranous coat ; and thus forming as many small 

 cells. The walls of the parent whose whole living substance has 

 thus been appropriated to the offspring, now burst asunder, and the 

 progeny escape. These rapidly increase in size until each acquires 

 the dimensions of the parent, when the contained matter is again 

 separated into new spheres ; giving rise to new cells, to undergo in 

 their turn the same changes. And as, under favorable circumstances, 

 but a few hours are required for this simple growth and development, 

 the production of the red snow plant is often very rapid : hence the 

 accounts frequently given of the sudden appearance of a red color in 

 the snow, over a wide space, which appearance is ascribed by common 

 report to the falling of bloody rain or snow. In many such cases it 

 is probable that the Frotococcus may have existed on the portion of 

 soil over which the snow fell, and its development may have merely 

 kept pace with the gradually deepening sheet of snow. That this 

 plant is not confined to the surface of snow is well known ; and Cap- 

 tain Eoss mentions that in many places where he had an opportunity 



