146 NYLANDER ON THE ALGO-LICHEN HYPOTHESIS, &C. 



tliesis. Those, however, who have promoted it have brought 

 forward nothing confirmatory of it, but only anatomical reasons 

 long ago well known (they have introduced nothing). The absur- 

 dity of such an hypothesis is evident from the very consideration 

 that it cannot be the case that an organ (gonidia) should at the 

 same time be a parasite on the body of which it exercises vital 

 functions ; for with equal propriety it might be contended that the 

 liver or the spleen constitutes parasites of the Mammiferce. Parasite 

 existence is antonomous, living upon a foreign body, of which 

 nature prohibits it from being at the same time an organ. This is 

 an elementary axiom of general Physiology. But observation 

 directly made teaches that the green matter originally arises within 

 the primary chlorophyll —or phycochroui — bearing cellule, and 

 consequently is not intruded from any external quarter, nor arises 

 in any way from any parasitism of any kind. This, in a note 

 *' Upon the Gonimic Evolution of the Collemaeei " (" Flora," 

 1868, p. 353), I have already enunciated, and in vain can it be 

 denied. The cellule at first is observed to be empty, and then, by 

 the aid of secretion, green matter is gradually produced in the 

 cavity, and assumes a definite form. It can, therefore, be very 

 easily and evidently demonstrated that the origin of green matter 

 in Lichens is entirely the same as in other plants. What need is 

 there then of any fuller refutation of the but too notorious hypo- 

 thesis of Schwendener ? 



In a note under this paragraph, Nylander adds — " To those 

 desiring somewhat longer explanations upon this subject, I may 

 transcribe the following observations which I have elsewhere 

 made : — ' In this place may be noticed the hypothesis, or singular 

 conjecture, which, confirmed by no certain observations, and de- 

 pending upon no valid grounds, amongst other statements, exhibits 

 Scytonemata insinuating themselves into the thalli of Pterygium 

 (erroneously termed P armaria in Schwend. Erorter, in " Flora," 

 1872, t. 4). Those Scytonemata are explained as ' Alga?,' which, 

 in a most wonderful manner, are parasitic in Pterygium." But did 

 not the author in conceiving such a theory know that the Scytone- 

 mata are (as is proved by the genus Gonionema), rather Lichens 

 than Alga? ; so that he was by no means treating of the parasitism 

 of an Algal on a Lichen, but of a Lichen on a Lichen. Moreover, 

 the Scytonemata present a gonimic vagina much firmer than the 

 Scytonemoid syngonimia of the Pterygia, and consequently the 

 Schwendenerian assimilation is entirely erroneous. In opposition 

 to the affirmation of this author, I may also add that no free 

 Scytonemata are to be seen in the specimens cited as received from 

 Tuckerman, and which I also have received. And if there were 

 any truth in his seeing anything of the kind, we would reason from 

 it that Lichens would grow best and occur most abundantly in 

 places where Scytonemata and other " Alga?," regarded as " para- 

 sitical" gonimic, or gonidial elements of Lichens, abound, and 



