100 JOURNAL OF PROCEEDINGS 
We will never, I think, find vegetation on the moon by 
seeking with the telescope for appearances such as our terres- 
trial forests and-fields present to the observer from a balloon. 
Another peculiarity which these lichens possess is the extreme 
slowness of their growth. One specimen observed by Mr. 
Crombie had not arrived at its maturity in 45 years. They are 
perennial plants in the widest sense of the term, and many defy 
the ravages of time for many hundred years. Indeed, “the 
life of lichens bears in itself no cause of death, and is only to 
be ended by external injuries,’ or by the alteration of climatic 
and atmospheric conditions. Hence the assumption is not 
unwarranted that individuals of such confessedly loag lived 
species as Lecidea Geographica, growing on rocks upon the sum- 
mits of lofty mountains date from more than ‘fabulous epochs,” 
and probably outrival in longevity the ages assigned to the old- 
est trees on the surface of the globe. 
If, as I believe, vegetation on the moon must be akin to the 
lichens, it is not at all likely it would possess the characteristics 
of growing to maturity and fading away again in the short 
space of 1434 days, possessed by the spots on the Moon, ob- 
served by Prof. W. H. Pickering and ascribed by him to vege- 
tation. Such growth is almost inconceivable of any vegetation 
when the thermometer does not rise above freezing point, and 
quite inconceivable of the forms of vegetable life found on 
earth to be associated with low temperatures. The variable 
spots ascribed by Pickering to vegetation were found between 
55 degrees N. latitude and Go degrees S. latitude. “The gen- 
eral phenomena exhibited by a variable spot,’ he says, “are a 
rapid darkening followed bv an equally rapid fading towards 
sunset.” “ At their maximum some of these spots are intense- 
ly black, some are a dark grey, and others a light grey.” 1 il- 
lustrate these spots by a series of drawings by Pickering, show- 
ing the gradual growth and fading of various dark spots in the 
interior of the crater Franklin. Whether the changes of 
these spots are due to real changes of the surface, or are due 
simply to shifting shadows I do not profess to say, but I do not 
think they are due to organic growth. 
