ALGyE, 21 "^ 



Trichophore. This latter is a body usually consisting of several cells, in or near 

 which the results of the fertilisation become apparent, cell-filaments or masses oi 

 tissue shooting out near or beneath it, forming the receptacle, here termed the 

 Cystocarp, in which the spores are subsequently formed. In one genus (Dudres- 

 naya) the process is still more complicated, inasmuch as tubes first spring from the 

 trichophore, which occasion the formation of the cystocarps only after conjugatior 

 with the terminal cells of other branches. 



In other Algae the result of the fertilisation is first of all the formation of £ 

 cell-wall round the oosphere, which thus becomes an oospore. In the Fucacea 

 this is at once capable of germination; but in other cases it does not germinat< 

 until after a long period of rest, like most zygospores. The product of the oospon 

 is, in the Fucaceae, a new plant of apparently similar description to the mother 

 plant; in GEdogonium, on the contrary, it produces several swarm- spores, eacl 

 of which forms a new cellular filament, of which in this case the plant consists. Ii 

 Coleochaete the oospore after the resting period developes a mass of tissue fron 

 the cells of which the contents also escape as zoospores. 



The Mode of Life of Algce is determined and limited by the concurrence o 

 two conditions, besides the specific requirements of temperature, viz. water an< 

 light. The greater number of Algae are submerged aquatic plants, or, whei 

 otherwise, they still require water for certain processes of development, especiall 

 for their reproduction; sometimes certain vital phenomena are caused by moistenin| 

 with water after the drying up of the cells. Light is a universal condition of the lif 

 of Algae, inasmuch as they are all dependent on individual assimilation ; in them 

 as elsewhere in the vegetable kingdom, this is brought about by chlorophyll, which 

 with the help of light, decomposes carbonic acid and evolves oxygen. Algae are 

 therefore, never true parasites \ although they very commonly live on the surface 

 of other plants. This at the same time affords the only means for a sharj 

 but artificial separation between Algae and Fungi. From the section of Siphoned 

 among the Algae containing chlorophyll to the parasitic Phycomycetes among th 

 Fungi destitute of chlorophyll there occurs so gradual a transition in their morpho 

 logical characters that, without the characteristic colouring, the Siphoneae and Phy 

 comycetes would have to be included in one group; but the distinction betweej 

 Algae and Fungi would then be at once overthrown. There exists in fact, a 

 may be concluded from what we have said, no definite boundary-line ; but fo 

 the sake of clearness it is desirable to estabhsh a conventional or artificial one 

 and this is best aff"orded by the presence or absence of chlorophyll. 'All Algs 

 contain chlorophyll, and have therefore the power of independent assimilation 

 all Fungi are destitute of chlorophyll, and are therefore parasites, or live oi 

 organised products of decomposition, and are in general independent of ligh 

 in obtaining their nourishment. The chlorophyll is generally concealed from th( 

 sight in Alg^ by the presence of substances of a different colour. The Nostocacea 

 appear, in spite of their chlorophyll, bluish- or light-green, because they contaii 

 in addition a colouring material soluble in water, which by transmitted light appear 



^ [This proves however not to be absolutely true. Cohn has discovered a chlorophyllaceou 

 Alga, Chlorochytrinm Lenince, which is parasitic on Lemna. Archer has collected the literature c 

 the subject in the Quart. Journ. Micr. Sc. 1S73, p. 366 et seq.— Ed.] 



