306 BOTANY. 



2. Scliwendener has shown* that the gonidia may be referred to well- 

 known groups of alga;, some of which belong to the Zygophyta, while 

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

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

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

 coccacese ; those of Graphis, Veirucaria, etc., with Chroolepidese (re- 

 lated to Conferva and GladopJiora) ; thos- ot Usnea, Cladonia, Physcia, 

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

 some other lichen gei>era are referred to still other alga groups. 

 V 3o 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 alga? are identical 

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

 that the mode of origin described by Speerschneider and Bayrhoffer is 

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

 nidia develop from the hyphae with which they are seen to be in contact. 

 The connection 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 lichen-cells, on the other they are held to be alga? belonging to en- 

 tirely different thallophytic groups. 



4. It must at once be evident to any one that 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 hyphae, or en- 

 tirely independent of them, as maintained by Scliwendener. 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 hyphse 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 hyphae 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, the 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 the offspring of 

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



* " Die Algentypen der Flechtengonidien," 1869. 



t This was long since shown by Itzijrsohn Botanische Zeitung, 1854, 

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

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

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



