212 The Philippine Journal of Science lan 
several feet. It is observed that the top layer of ash has formed a crust, 
but this has been broken up at frequent intervals by heavy rains; the 
result is that numerous shallow water-channels have been formed. It is 
observed that it is only in these depressions that plants have been able to 
get a root-hold. The chief plant lining the sides is the silver fern {Gymno- 
gramme calomelanos, Kaulf.) [ — Ceropteris calomelanos Und.], which is 
playing the important part of preparing the ash for higher types. Already 
a few hardy plants such as the hurricane grass (Arundinella martinicensis, 
Trin.), Einilia sonchifolia, DC., cattle-tongue {Pluchea odorata, Cass.), 
Eupatorium odoratum, L., and a sedge or two are found growing with the 
ferns. Here it is evident that these are the true ash plants, and have 
grown from spores and fruits brought by wind and water; but chiefly by 
the former. 
Areas, in which the destruction of the vegetation was not com- 
plete or where the ash has subsequently been largely washed 
away, have become covered with plants. 
On the upper slopes of the volcano revegetation has been slow 
as will be seen from the following statement by Sands : 
At 1,400 feet, plants are scantily distributed and the growth is poor. 
Only the hardy bamboo and Roseau grasses, silver ferns and tree-ferns, 
Freziera hirsuta, Sw., and Eupatorium odoratum, L., appear to thrive. 
Here, howeyer, is found the pretty moss Lycopodium cernuum, . L., and the 
somewhat rare Eupatorium ossaeanum, DC. At 2,000 feet, silver ferns 
and mosses only are seen. From this altitude to the lower lip of the crater, 
which aneroid barometer readings indicate to be 2,800 feet above sea level, 
the ejecta assume a coarse, cindery form, in which at present only algae, 
mosses, and lichens are able to exist. 
According to Anderson,®® the early stages of the revegetation 
of Mount Pelee were similar to those of the Soufriere. 
In view of the fact that both the chemical and the mechanical 
compositions of volcanic ejecta vary greatly, it is not surprising 
that the effect on plants should be different in different cases. 
Probably the most usual condition is for recent ejecta to form 
a poor substratum for plants. This is particularly true of lava 
flows, which have to be weathered very considerably before they 
can support higher plants. Very interesting examples of this 
phenominon have been described from the Hawaiian Islands by 
Rock. 
Even when the ejecta form a soil composed of fairly small 
particles, such a soil is very frequently a poor substratum for 
plants until a considerable period has elapsed, when the soil has 
apparently been weathered and leached. 
Anderson, T., Phil. Ti'ans. Roy. Soc. London Sec. A. 200 (1908) 275-303. 
Rock, J. F., The indigenous trees of the Hawaiian Islands. Honolulu 
(1913). 
