306 BOTANT. 



2. Schwendener has sliown* tliat the gonidia may be referred to well- 

 known groups of aljrse, some of which belong to the Zygophyta, while 

 others belong to the Protopliyta. Thus the gonidia of Collema, Lepto- 

 gium (including MaMotium), Peltigera and some other genera, are iden- 

 tical with Nostocaceae ; those of Omphalaiia and others, with Chroo. 

 coccaceae ; those of Qraphis, Vei rucaria, etc., with Chroolepidese (re- 

 lated to Oonferi)a and Gladophora) ; those of Vsnea, Oladonia, Physeia, 

 Parmelia, and most higher lichens with Palmellacese. , The gonidia of 

 some otlier lichen gepera are referred lo still other alga groups. 



3. When gonidia are dissected out from the lichen-thallus they are 

 capable of Independent existence ; and there can be no doubt that (as 

 De Bary intimated) many of the forms regarded as algae are identical 

 with gonidia.f With these facts before us, it can scarcely be doubted 

 that tlie mode of origin described by Speerschneider and Bayrhoffer is 

 incorrect. There cannot now be shown any good evidence that the go- 

 nidia develo|,> from tbe hyphae with wliich tliey are seen to be in contact. 

 The connecti'~n between hyphae and gonidia is doubtless one which takes 

 place after the origin of the latter. The two remaining views — i.e., 

 Schwendener's and Minks' — agree upon this point, and in both the idea 

 of a genetic connection between gonidium and the hypha-filament in 

 contact with it is rejected. These two theories, however, differ radi- 

 cally in this, that while on the one hand the gonidia are regarded as 

 true liclien-cells, on the other they are held to be algae belonging to en- 

 tirely different thallopliytic groups. 



4. It must at once be evident to any one thut the actual relation of 

 the hyphal portion of the lichen to the gonidia is the same whether the 

 origin of the latter be, as asserted by Minks, within the liyphae, or en- 

 tirely independent of them, as maintained by Schwendener. Any con. 

 nection which subsists between these two can be, under the circum- 

 stances, of only one kind, namely, that of a greater or less degree of 

 parasitism. It makes no difference to show that the gonidia are derived 

 from the hyphae themselves, for they are (it is said) set free after their 

 formation in the mother-cell ; now any subsequent connection of these 

 green cells with the hypliae cannot possibly have any other meaning 

 than that the latter derive nourishment from them. The only differ- 

 ence between the two theories may be expressed in this way : according 

 to the one, tl)e imprisoned slaves which furnish nourishment for the 

 hyphal master are members of entirely different groups of the vegetable 

 kingdom ; while according to the other, the slaves are tlie offspring of 

 the hyphal master which imprisons them. In the first the gonidia are 



* " Die Algentypen der Flechtengonidien," 1869. 



f This was long since shown by Itzigsohn — Botanimhe Zeitung, 1854, 

 by Hicks — Qr. Jour, of Mic. Science, 1861 , and by Famintzin and Baranet- 

 sky — Botanisehe Zeitung, 1867 ; Nylander also arrived at the same con- 

 clusion with regard to the gonidia of Collema — Flora, 1868. 



