8 4 
Peirce . — A Contribution to the 
the cuttings do not receive suitable or sufficient food from the 
plant which they have attacked. That this is really the case 
is shown also by a continuation of the previously described 
experiment of putting cuttings of C. glomerata on suitable 
branches of an Impatiens. The cuttings become green while 
they are coiling around and sending haustoria into the host. 
The green colour remains intense for a few days, then it 
begins to fade, the new parts are all yellowish, and finally the 
new plant, with the exception sometimes of the first close coils 
made, is as yellow or orange in hue as the plant from which it 
was cut. In this case the lack of suitable food is only 
temporary, and when it has ceased to exist, the Cuscuta no 
longer needs to be as nearly self-dependent as possible, no 
longer forms chlorophyll, but returns to its absolutely or 
almost absolutely parasitic condition. Such, however, is not 
the case when the branches of C. Epilinum are put upon 
a Euphorbia. Although haustoria are formed in numbers 
adequate to draw from the host food sufficient in quantity, 
yet the quality of the food, whether owing to the poisonous 
matters which Euphorbia is well known to contain, or owing 
to less evident causes, is unsuited to the parasite. It never 
returns to the healthy yellow or orange hue which marks it 
as a parasitic plant. 
When the entrance of haustoria into a stem about which 
a Cuscuta has formed close coils is delayed by thick opposing 
cuticle, strong sclerenchyma, or intense silicification of the 
peripheral cells of the host, there takes place in the branch 
a more or less evident change in colour according as the 
haustoria attain their goal more or less slowly. Such is the 
case when branches of Cuscuta are brought into contact with 
leaves of Aloe , and with the stems of Juncus and Equisetum . 
As might be expected, the parasite does not flourish on these 
plants, for the difficulty of penetrating them is not set off by 
more abundant or more nourishing food than that more easily 
obtainable from other plants. On the contrary, the secretions 
of the Aloe seem to be decidedly poisonous, the haustoria not 
developing well after they have finally reached the fleshy 
