t4 HEDWIG ON THE ORGANS Olf 



From the first three figures frl. I.) it appears 

 that the acute angles of the apertures do not ex- 

 tend so far as to touch the margin of the area ; 

 which is the ease in most plants I have examined. 

 In the Indian corn (Fig. 6.) however, they come 

 very near to the upper and lower corner of the 

 quadrangular receptacle. In the grasses, these 

 apertures are longer than in other plants, at least 

 in proportion to the receptacles ; for they extend 

 to the very limits of the areasi This is, perhaps, 

 the reason why they have two different ways of 

 opening and closing ; for they are either contracted 

 in the middle, and remain open at both ends, (as 

 represented in the Indian corn, Fig. 6.), or their 

 ends are contracted, while the fissure remains open 

 in the middle for about one-fourth of its length 5 

 as I observed in the leaves of oats. 



I have before observed, that lymphatic vessels 

 are found in both surfaces of the leaves, and such 

 parts as are analogous to them; but, with respect to 

 the described apertures and areas it is quite other- 

 wise. They indeed are often, though not univer- 

 sally, found in annual and biennial plants on both 



