SPECIAL MORPHOLOGY: ALG^E. 145 



(Lichens), or Mycoderma (Fungi ?) from Protococcus (Algae), by 

 characters belonging to groups, and scarcely even generically. We may 

 separate them more safely by looking at the whole series of development ; 

 but even here the boundaries, as especially between Algce and Fungi, 

 when the latter grow in water, are confused, and between Fungi and 

 Lichens there are at least transitional forms which it is difficult to bring 

 into a definite position. 



If we look, on the one hand, at the often naked fruits of the gelatinous 

 Lichens and the species of Peziza, and on the other at the Sphcerice, 

 whicn agree with many of the Lichens, we soon see that no very marked 

 difference can be established between Lichens and Fungi from their con- 

 ditions of consistence or structure. If we join the Pyrenomycetes and 

 the Discomycetes to the Lichens, which, as far as regards the former of 

 the two, appears in conformity with a natural arrangement, and is not 

 very extravagant with respect to the latter, if we look upon a Peziza, 

 for instance, as an Apothecium with the thallus (the mycelium) obli- 

 terated the formation of the spores within the sporangium ( Thecce) 

 would in that case be characteristic of Lichens. For the sake of the 

 facility which jt affords in the treatment of the subject, I shall adopt 

 this mode of subdivision, without, however, laying any peculiar stress 

 upon its importance. To me it appears evident that whoever has ac- 

 curately observed both groups must see the little value that is to be 

 attached to the difference of the thallus (in the Lichenes) and the stroma 

 (Fungi), (owing to a few green cells in the former,) as characteristic of 

 the two groups. One is disposed to assert that all botanists have ab- 

 stained from placing most Sphcerice and Hysterics under the head of 

 Lichens solely because their teachers had told them that they were Fungi. 



We obtain the following divisions from the form of the spores: Spores 

 which develop themselves (from 1 to 4) in the sporangium according to 

 the second form of cell formation Algce; spores which to the number of 

 eight to ten are formed in the sporangium according to the first form of 

 cellular formation Lichenes; and lastly, spores developed individually in 

 smaller lateral expansions of the sporangium, separating themselves with 

 it Fungi* 



L ALG^E. 



80. The propagating cell (the spore) constitutes, in some rare 

 cases, the whole plant (Protococcus, &c.). More generally, however, 

 it expands itself during its development to a long, thread-like, often 

 ramifying cell ( Vaucheria) ; or it forms, in a manner with which we 

 are as yet unacquainted, many other cells, variously and multi- 

 fariously arranged, and thus constitutes the plant (frons Auctor). 



The simplest forms exhibit waving ( Undind) or straight rows of 

 spherical cells interspersed here and there with whorls of lateral 

 branches (Batrachospermuni) : in other cases the cells acquire the 

 form of cylinders attached together so as to compose longer or 

 shorter filaments. These threads are either simple, or are them- 

 selves ramified in various ways so as to constitute a closed net 

 ( Confervacece). These plants generally secrete a definitely formed 

 gelatinous layer, which in the case of the Nostochinece determines 

 the form of the whole plant, while in that of the Confervacece it 

 constitutes only a membranous investment of the individual threads. 



L 



