296 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE, 
“opposition of stem and root,” none of the distinctions which 
Endlicher pointed out are available now; least tenable of 
all is the absence of sexuality in the Thallophyta. 
The classification of the vegetable kingdom by A. P. 
De Candolle into VascuLARES and CeLLuLaRus (1813) is far 
inferior to Endlicher’s, though still in use. The two terms 
do not properly contrast, and the inclusion of the Muscinee 
among the Cellulares is entirely unnatural in the light of our 
present knowledge. 
For the last half century the Thallophyta have been held 
to fall into the three district groups of Alge, Fungi, and 
Lichens ; these were first limited as they now stand by Bishop 
Agardh (‘Aphorismi Botanici,’ 1821). 
The autonomy of the Fungi had been recognised by the 
oldest systematists, and as early as 1583 Cesalpinus in- 
cluded under that head at any rate the larger forms which 
are so designated now. But A/ge down to the time of Linneus 
were mixed up with Hydrozoa, Actinozoa, and sponges. 
The group, since so-called, was established by him in 
1735; but while he purged it of Lithophyta he retained in it 
Hepatice, Lichens, and Rhizocarpee. Jussieu (1789) sepa- 
rated the Hepatice, and his Alge consisted of the plants at 
present recognised as such together with Lichens. 
Considered as mere convenient assemblages or depositaries 
to which plants might be referred, the division of Thallophyta 
into Alge, Fungi, and Lichenes, has worked tolerably well. 
And although it was found impossible to characterize the 
groups morphologically in the vast proportion of cases, little 
difficulty was found in referring any particular Thallophyte 
to some one of them. Berkeley and Lindley (1845) found 
themselves obliged to limit them by physiological cha- 
racters : Alge, generally speaking, they regarded as aquatic ; 
Fungi and Lichenes as aérial. ‘The former, however, drew 
their nutriment from their substratum,while the latter obtained 
it from the air. 
This classification was adopted without question until 
1868, when Prof. Schwendener, of Basle, propounded his 
now famous theory, that Lichens are not autonomous but 
composite organisms, consisting partly of an alga, partly of a 
fungus which forms a filamentous network in which the cells 
of the alga (‘‘ gonidia”’) are imprisoned. While the latter is 
probably identical with forms met with in a free state the 
fungoid part of the lichen is only known as a parasite. In 
the volumes of this Journal for the last two years! notices 
will be found of all the more important papers in which 
1 «Quart. Journ. Micros. Science,’ 1873, pp. 217, 235; 1874, p. 151. 
