BoT.— Vol. I.] rEIKCE-h^ATURE OF LICHENS. 213 



discharged, both in nature and in the laboratory, before 

 they are ripe and whenever the apothecia are wet. Second, 

 that by bearing this in mind and by using trustworthy cul- 

 ture media for such cover-glass preparations, subjecting 

 them to otherwise normal conditions of warmth, light and 

 aeration, the percentage of ripe spores capable of germina- 

 tion could be determined. From these data the relative 

 values of the spore -method and the purely vegetative 

 method of dispersal could be ascertained. This is, how- 

 ever, hardly necessary, for, as I have shown in a previous 

 paper (1898), the great majority of the specimens of R. 

 reticulata to be found about here are evidently fragments, 

 while only very few have grown where they are from the 

 spore. This lichen may, earlier in its history, have pro- 

 duced even more spores in each apothecium and more 

 apothecia than now, but this would seem hardly necessary, 

 considering the ease with which fruiting specimens and an 

 abundance of spores may be obtained at all seasons. It 

 seems more probable that in this lichen, as is claimed also 

 for others, superiority of the purely vegetative method of 

 dissemination (by means of fragments torn away by the 

 wind) is resulting in the decrease of the germinating power 

 of the spores. 



The superiority of the vegetative method of reproduction 

 is two-fold: it insures the presence in the new place of 

 both members of the lichen association — the hyphse and 

 the gonidia, as is the case in the soredia of other lichens — 

 and it results in much wider dispersal than is possible with 

 spores or soredia. The vegetative method of dissemination 

 of this lichen, so evidently a very valuable one and perhaps 

 the most perfect among lichens, may well react on the pro- 

 duction of spores; if not already as to their number, then 

 certainly as to their quality. 



Although the spores germinated in the same length of time 

 and in about the same numbers (proportionally) in the agar- 

 agar, gelatine and water cultures, the subsequent develop- 

 ment was unequal. In three days after the first germina- 

 tions were observed, the germ-tubes had grown somewhat 



