BRIEFER ARTICLES 
ARTIFICIAL PARASITISM: A PRELIMINARY NOTICE. 
SOME years ago, in the course of an investigation suggested by Prerrzr 
to show that ordinary roots, as well as those of parasites, can penetrate 
living tissues, I succeeded in growing a pea (Piswm sativum) on a plant of 
horse-bean (Vicia Faba), at least so far that the pea blossomed and set seed.’ 
At intervals since that time I have grown peas on plants of the same bean, 
with success varying according to the very unideal conditions under which 
I have experimented. Some of the results obtained seem worthy of pub 
lication now, although I have only begun a piece of work which I hope t0 
carry on for years to come. 
The main object of the investigation is to ascertain how an independent 
plant will behave when compelled to lead a parasitic or partially parasitit 
existence; what the changes, immediate, successive, and cumulative, may 
be in successive generations. ‘ 
The method so far pursued is this. Pea seeds of “extra early” varieties 
soaked in water for twenty-four hours, are placed, radicle downward, it 
bulb pots of fine sand, and allowed to germinate until the radicles a 
1-2™ long. The seeds are now ready for setting on the beans. Thest 
are plants of Vicia Faba, 30°™ or more tall, grown two or three in each pot 
Care is taken to select for experiment only strong plants, although T cannot 
see that the peas injure the beans on which they grow. Ata height of about 
15°" above the soil I cut a hole, with a taper-pointed, sharp, clean ee 
in the stem of the bean, the hole being about as large as the radicle — 
pea selected for mounting on the bean plant. Into this hole the 
is gently pushed, passing into the cavity of the hollow stem, until the oF 
ledons are close against the stem. A strip of writing paper is nOW gee 
ped about the stem and fastened with sealing wax as to forma conical : 
he cotyledons 
Int : ae 1s overs t 
0 this plaster of Paris is poured until it all but c vith upward 
de deep enous? 
east 
sare 
Bot. Ze 
In this way the pea is held in place without interfering 
growth of the plumule. In dry weather the molds are ma 
to hold a layer of wet saw-dust 1°™ or more deep over the 
is unnecessary, however, in damp weather. When the pea-plan 
* Peirce, G. J., Das Eindringen von Wurzeln in lebendige Gewebe. , 
52: 169-176. 1894. 
214 
