On the Nourishment produced to the Vlani ly its Leaves. 7 



the root and niirse plant, some from tlie atmosphere and nurse 

 plant. There are however others, that, not satisfied with draw- 

 ing from the exterior or bark of the tree, dive deep into it, and, 

 running a large vessel from one pump to another, lay asort of clainj 

 on the w^ood, that must be highly prejudicial to their nurse. Of 

 this kind is the viscum, and many West India climbers ; which 

 will often bind the wood as cruelly within, as the ivy does at the 

 exterior of the plant. There is besides a peculiarity belonging 

 to most parasite ])lanl;s that deserves notice ; they v/ill often 

 show, bv some change of form, how much support tliey gain or 

 lose from tlieir nurse. Thus the \vy alters its leaves the moment 

 the pumps are no longer suspended on the side of the tree, be- 

 cause then the greatest quantity of food comes from the root, 

 and the juices of that part are no longer balanced by those which 

 it received from its pumps. The orobanche draws much from 

 the atmosphere the last few weeks of its existence : the taller, 

 therefore, it grows, the more imlike itself it often becomes ; and 

 I found three last year, whose upper leaves were almost lier- 

 baceous, and had lost all that stringy woven appearance the 

 orobanches are so famous for. But the most curious alteration 

 I ever experienced in a parasite plant was that produced in an 

 ophrys nidus avis, which had fixed its principal roots on the roots 

 of a birch, and was covered some inches above the ground with 

 dead leaves, to which its quantity of small sponges adhered. It 

 exceeds the orobanckes in these appendages, but they are always 

 above the ground, instead of under ; but they were not as in that 

 plant loose, one side adhered to birch and one to oak leaves, 

 and each side of the plant not only differed in colour, but the 

 scalv sheath v/as of a different texture. I was never so happy as 

 to find the plant but once, and I hope next year to be more 

 fortunate. 



All the pumps of the parasite plants proceed from and Efre 

 formed in the wood only, and may be traced directly to it ; there- 

 fore the juices are evidently drawn in to supply the place of sap: 

 another convincing proof that the sap runs only in the wood. 

 But when its pumps proceed as far as the wood to acquire its 

 juices from the nurse plant, then indeed it does verv great 

 damage, and this is always the case in the viscmni ; it then soon 

 spreads the rot through the body of its supporter. As to the 

 formation of the leaves of the parasite plant, this generally de- 

 pends on the circumstance, whether the leaves do or do not re- 

 ceive mohtuTC Jrom the ntmosphere. If they do not, as in the 

 ivy, their leaves are then formed like the evergreen ; if they do, 

 they are formed like the sheaths of tlie orobanche. 



1 must now mention a species of plants which I did not at 

 A 4 first 



