66 Peirce . — A Contribution to the 
a constant supply of water was conducted by a fine siphon (.r) 
into the paper cup (e) at the upper and uncoated end of the 
gelatined rod. From this cup the water flowed slowly and 
uniformly over all parts of the 
gelatine and was conducted away 
by the drainage-tube ( d ) to the 
catch-bottle ( b ). The hole at the 
bottom of the moist-chamber was 
closed by cotton wadding and the 
hole in the glass cover was nearly 
closed by a split cork. In the 
course of its circumnutation the 
Cuscuta came into contact with the 
rod, the nutation was delayed by 
the rigid obstacle, but the stem 
did not twine. Later, however, con- 
tact with the gelatined rod having 
been repeatedly broken and re- 
newed in the course of the nutation 
of the stem, the plant began to climb 
up the rod, making long, steep turns 
about it. These processes lasted 
eight days. On the ninth day, the 
stem, having reached the upper and 
uncoated part of the rod, at once 
made short, close turns about the glass and began to form 
haustoria. Control experiments with uncoated rods of glass 
and wood, wetted and dry, of rods coated with gelatine but 
not wet, in similar moist chambers, showed that contact 
always induced the formation of close turns and of haustoria. 
Hence it is evident that it was not the water which inhibited 
close winding, but merely the non-irritant nature of wet 
gelatine. 
These experiments repeated with plants of all three species 
invariably gave the same results. We see, therefore, that the 
formation of close turns is always dependent upon contact- 
irritation ; that Cuscuta is, as others have asserted, irritable to 
