870 WILLIAM ARCHER. 



host-animal, in the unequal struggle.' Such, " popularly '^ 

 expressed, is Schwendener's view as to " Lichens " at large, 

 which he now holds and supports. This quotation, I Avould 

 venture to suggest, would seem sufficiently to convey its own 

 refutation of the hypothesis, inasmuch as this assumed para- 

 sitic fungus does not destroy or live upon its assumed algal- 

 host. If the " parasite " cannot be a " fungus " it must be 

 something else — that something else no more nor less than the 

 veritable "lichen," though it may be, indeed, but in part re- 

 presented ; though, of course, on all hands it is agreed that 

 Lichens and Fungi, save the gonidia, have between them no 

 absolute line of demarcation. 



Seemingly, at first, more impressed with the applicability 

 of Schwendener's hypothesis to the Collemacese, though he 

 no doubt afterwards accepts its complete tenability as regards 

 the whole class of the " Lichens," Keess conceived the idea 

 of " sowing " the sjjores of Collema upon the substance of 

 Nostoc, and a description of the experiment and its results 

 forms the subject of his memoir previously alluded to.^ He 

 states, indeed, that the spores of Collema can be readily 

 enough made to germinate upon any moist substratum, such 

 as a glass plate, stones, and so on, and will slowly produce 

 even a branched and sparingly jointed growth, but this goes 

 on only so long as the reserve-stuff is supplied by the spore, 

 but when this is exhausted the hypha-mass thus produced, 

 though it may survive even weeks, will then slowly die off. 

 But when he brings a spore or the young hypha upon the 

 Nostoc, it at once becomes further developed, sending more 

 or less co^jiously through its surfaces many branches, and 

 penetrating within. Soon, however, they cease to increase in 

 length, become swollen at the points and at other places, and 

 become attached by these swellings upon the Nostoc. There- 

 upon thinner processes become sent further into the gelati- 

 nous mass of the Nostoc, from the swellings ; these become 

 branched, and, tortuously surrounding the chains of gonidia, 

 form, in fact, the " Collema-mycelium," and the complete 

 transformation or conversion of the " Nostoc " into the 

 Collema is brought about by the hypha producing a peri- 

 pheral stratum of fibres, from which break forth, through the 

 " Nostoc-jelly," the first root-hairs. Such an artificially 

 produced " Collema " the author had not been able to rear 

 up as far as the production of fructification (apothecia), but 



^ Scliwendener, 'Die Algentypen,' &c., p. 3. 



' Prof. Reess, ' Ueber die Entstehung der Flechte Collema glcmcescens, 

 Hoffm., durcli Aussaat der Sporen derselben auf Nostoc lichenoides, Vauch.' 

 in "Monatsb. der k. Akad. der Wissensch. zu Berlin," Oct., 1871, p. 523. 



