10 Director's Report for 1916. 
being completely scorched. Looking across the flow the scorching 
of foliage on the lee side did not appear to be very much greater than 
on the windward side. Practically all vegetation on the windward 
side of the flow at a distance of two feet and often less survived. 
Minor effects on vegetation were the plowing up of sods by great 
angular blocks of rock pushed forward by the flow; and the effect 
of either steam or gases escaping through underground passages 
along the edge of the flow, which in one case observed caused the 
destruction of a large koa tree at a considerable distance away from 
the lava stream. It is hardly necessary to mention that all vege- 
tation in the course of flowing lava was annihilated. I observed 
nothing which suggested the effect of poisonous gases, withering 
being caused by heat, as was indicated by the relative position of 
scorched and green foliage. Weather conditions during the period 
of the flow were not particularly favorable for the development of 
forest fires, and I was not able to ascertain if any took place. 
‘““Along a crack extending from the source of the eruption, 
which is above Puu o Keokeo, toward the summit of Mauna Loa, 
I observed blighting of vegetation which I believe was caused by the 
emission of poisonous gases. While not impossible that this was 
caused by frost, the relative appearance of the damage done to 
different bushes bore a decided relation to the distance from the 
crack. At an estimated distance of three hundred feet on the lee 
side of this crack bushes of Dodonea viscosa had blighted leaves; 
while closer in leaves of Vaccinium penduliflorum and Coprosma 
ernodeoides were blighted. The foliage of Cvathodes Tametametae 
which is needle-like was not affected, but buds of plants rather 
close to the crack were blighted. In all cases the blighting was 
slight and the plants probably quickly recovered. 
‘‘At the source of the eruption there is a small area of Aahoe- 
hoe java; many of the characteristic cracks of this fresh lava had 
a whitish discoloration or an otherwise different appearance in 
color from the rest of the lava, due to the action of escaping gases 
on the rock surface. This fact is especially mentioned here be- 
cause it probably bears an important relation to the future invasion 
of plants. ‘The chemical nature of the surface of the cracks must 
be somewhat different from the surface rock of either fahochoe or 
aa. I have noticed this surface discoloration in the cracks of all 
old pahoehoe flows, but was never quite sure whether it was purely 
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