
* 
AS APPLIED TO PHYSIOLOGY. 239 
I noted one specimen of the gigantic sort in which a branch 
of parasite, after leaving the stem, passed up the petiole, then 
along one margin of the leaf, then in its twist coming across 
a smaller leaf in the axilla of the next leaf, adhered to its 
footstalk, then back again to the leaf to which it first ad- 
hered, and thence passing off in quest of other prey. The large 
leaf did not seem to suffer, the small one was sphacelated 
at its apex. À 
In a hedge at Bamean, I observed, I believe, the same 
species growing on a kind of Hippophae, and attacking 
every other plant within its reach, here seizing, on a Hæra- 
cium, there a Hyoscyamus, on this side attacking a Willow, 
and lastly encroaching on a cornfield on one side of the 
hedge, and forming a confused mass of adhesions with the 
various plants along its border, not excepting the Grasses 
themselves. 
Possibly in this case the angles so described are distinct 
axes! they certainly appear to be so in the sketch I have 
before me. 
But its voracity is capable occasionally of greater extension, 
for if, as happens in the case of the Cabul Poplar, the surface 
of the wood presents out-cropping angles, offsets will be found 
sent to the nearest of these, from the main sucker within the 
bark. oe 
The whole substance of the circumferential system of the 
Cuscuta appears to pass inwards, and to be expanded on the 
surface of the last formed wood. I did not always observe 
a passing in of the ligneous system, but this was evident 
enough in cases of parasitism on Alhagi Maurorum, and here 
the external system adhered to the bark of the stock. 
In Orobanche the suckers have the same inclination to 
become mutually attached: but independently of their being 
confined to the roots, there is another striking difference, 
since the attachment takes place by the central or ligneous 
system alone, by means of ducts which passing off from the 
outermost ducts of that system, pass through the cellular 
external system, thence through that of the stock, terminat- 
