PERSPIRATION OF PLANTS. It 



parenchyma are often observed in these areas, in 

 greater or lefs quantities ; but are never found in 

 this case to extend so far as to the circumference 

 of the area, from which they are separated by a 

 light coloured streak that resembles one of the 

 communicating ducts, and the inner side of which 

 is more closely covered with them. In many cases not 

 grains at all appear in the areas (PI. 1. Fig. i. 2. 

 5. 6.); nor do they forma constituent part of these 

 organs, for they are not, as it appeared to Von 

 Gleichen, incorporated with, but only adhering to 

 the inner surface. 



The number of the lymphatic vessels, or per- 

 spirative ducts, communicating with the areas, arc 

 Subject to variation ; but there are generally four 

 fas appears from the figures) or only two, as in 

 the leaf of the pink. Those that are irregular in 

 their direction, vary also in this respect ; so that 

 for instance in areas which should have four of 

 them, three, two, or one only, are found inserted. 

 This last case, however, is very rare. 



The place of their insertion is generally at the 

 sides of the oval bodies ; or, if there be but two 



