320 BOTANICAL GAZETTE [MAY 
It can be seen readily that it is possible to obtain all stages 
of reduction between mesophytic and xerophytic conditions. 
This depends on what stage in the normal life-history is attacked 
by the fire, and on the intensity or entire absence of subsequent 
fires. Thus all possible combinations are represented. ig. 77 




Fic. 15.—A young jack pine forest on a fossil beach near Marquette. The 
humus content of the soil has been much reduced by insolation and repea ated fires. 
The undestroyed Norway pines in the background probably indicate that the beach 
had formerly attained the Norway pine stage in the life-history series. 
shows a maple-hemlock forest that has been nearly destroyed 
by fire. This is situated on the slope of a quartzite hill, and had 
probably reached the climax condition. In places the fire has 
left remnants of the forest, and even where the trees are 
destroyed certain geophilous forest herbs like Clintonia borealis 
have maintained themselves in the shade of half burned logs, 
while near by fireweeds, poplars, and pines are found. Fug. 18 
shows an almost pure birch forest. Not far away, however, are 
