SKASOXS IX SoriUKRX ARIZOXA 



197 



lowing December or January, eight or nine months later, the 

 period of activity being comprised within a compass of a 

 hundred days. Some, however, like Covillca, with varnished 

 leaves, and a itw other species with hea\v protecti\e coatings 

 of cutin or hairs on the foliar surfaces, retain these organs 

 during a great part of the year, and derive some benefit from 

 the activity of the chlor()ph\l during the intense insolation of 



Fit;. 4. — 'I'lic ("iciisiit<- Imsii K'nvillir-a tri(U'iitata. 1 



the summer months. While the soil is supplied with water in 

 fair plenty, at least during the early part of this season, yet 

 humidity of the air ranges between 30 and 4() per cent and 

 only plants with protected surfaces may function to acivantage 

 in it. 



fVuiter (Uiniuils. Of the large number of herbaceous 

 forms which spring from germinating seeds in the wet winter 

 season and soon pass the whole cycle of existence, a few of the 



