ii6 American Quarterly Microscopical Journal. 



THE CLASSIFICATION OF THE ALG.E. 



BV A. B. HERVEY, A. M. 

 {^Received December \<)th, 1878.) 



I shall attempt, in this paper, to give the most important 

 results of the latest published studies of the Algae, in so far as 

 these bear upon the question of classification. 



In no department of Botany has the application of the prin- 

 ciples of the '' natural " as distingoiished from the '* artificial " 

 systems of classification, produced more important results than 

 in that of the Algae. The life-histor\' of the plant is now 

 made the principal basis of classification. The affinities of 

 form, structure, and color, are subordinated to that. The Col- 

 ochtzte. for example, though a green, fresh-water Alga, and 

 formerly classed with those of like habitat, color, and appear- 

 ance, is now removed on account of its known reproductive 

 process, quite away from the green, and even above the olive- 

 green marine Algae, and placed along-side of the red marine 

 Algae in the highest group of the series. Further, the biologi- 

 cal basis of classification arranges the Algae and the Fungi in 

 two parallel series, and puts the Lichens in the upper groups of 

 the Fungi, among the Ascomycetae. The only characteristic 

 difference recognized between the Algae and the Fungi, is a 

 difference in cell-contents ; the Algae containing chlorophyll, 

 and the Fungi having none. This must be reckoned more of 

 an " artificial " than a " natural " element of classification, as 

 it does not seem to influence, in the slightest degree, the repro- 

 ductive processes of the plants, these processes being quite 

 alike in the various corresponding groups in the two parallel 

 series. There is, indeed, an element of some importance in 

 the life of the plant depending upon the presence or absence 

 of chlorophyll in the cell ; viz., the ability of the plant to live 

 on organic or inorganic food. An Alga is able to subsist on 

 elemental food ; but the lack of chlorophyll in the Fungus, 

 compels it to seek its nourishment from living plants, or from 

 the decaying matter of organic substances, vegetable or ani- 

 mal. The following is the scheme of classification as proposed 

 and worked out by Sachs (Lehrb. d. Bot. Vierte Auf., p. 248). 



