104 VEGETABLE ORGANOGRAPHY. 



All these hairs are more or less like the lymphatic 

 in their form, but they differ in their origin, and seem 

 to be simple strips of an atrophied membranous surface ; 

 thus, the hairs of the pappus are evidently the rudiments 

 of their calyx, and the tufts which crown several 

 seeds, are like the membranes which border them in 

 analogous plants. Each of these kinds of hairs will be 

 spoken of more in detail when we treat of the general 

 organ of which they form part. 



I mention these Scaly Hairs here only for the purpose 

 of remarking, that although in some cases they may 

 serve, like the Lymphatic Hairs, to protect certain 

 delicate organs from cold^ insects, wet, or the too strong 

 action of light, they have in general an entirely peculiar 

 function, determined by their hygroscopic faculty : thus 

 the hairs of the pappus of Compositag remain upright 

 as long as they are moist, and have a tendency to fall in 

 proportion as they become dry ; in falling, they lean either 

 upon the involucrum or upon the neighbouring flowers ; 

 and not being able to separate them, they re-act upon the 

 fruit to which they are attached, and raise it out of the in- 

 volucrum ; then the least wind which happens to blow on 

 the kind of network formed by the radiating hairs of the 

 pappus, lifts it up and carries it away with the fruits. 



These hairs, then, are found to serve eminently for 

 the dispersion of the monospermous fruits of the Com- 

 posita? : it is also remarked that where they are absent, 

 there always exists some other circumstance in the 

 organization which supplies their place ; sometimes, as 

 in Anthemis, the receptacle rises in the centre, and 

 pushes the fruit out ; sometimes, as in Chrysanthemum, 

 the scales of the involucrum fall when mature ; at 

 others, as in Carpesium, the head of flowers leans over 

 when the fruits are ripe, in such a manner that they fall 

 out by their own weight, &c. 



