Guar. II. INFLECTION INDIRECTLY CAUSED. 27 
Accordingly measured lengths of a narrow strip of 
blotting paper, of fine cotton-thread, and of a woman’s 
hair, were carefully weighed for me by Mr. Trenham 
Reeks, in an excellent balance, in the laboratory in 
Jermyn Street. Short bits of the paper, thread, and 
hair were then cut off and measured by a micrometer, 
so that their weights could be easily calculated. The 
bits were placed on the viscid secretion surrounding the 
glands of the exterior tentacles, with the precautions 
already stated, and I am certain that the gland itself 
was never touched; nor indeed would a single touch 
have produced any effect. A bit of the blotting-paper, 
weighing ;4, of a grain, was placed so as to rest on 
three glands together, and all three tentacles slowly 
curved inwards; each gland, therefore, supposing the 
weight to be distributed equally, could have been 
pressed on by only +,!,; of a grain, or 0464 of a milli- 
gramme. Five nearly equal bits of cotton-thread were 
tried, and all acted. The shortest of these was 3, of 
an inch in length, and weighed ;,, of a grain. The 
tentacle in this case was considerably inflected in 
1 hr. 30 m., and the bit of thread was carried to the 
centre of the leaf in Lhr.40m. Again, two particles 
of the thinner end of a woman’s hair, one of these 
being +4 +42, of an inch in length, and weighing ,,1+, of 
a grain, the other ;42, of an inch in length, and weigh- 
ing of course a little more, were placed on two glands on 
opposite sides of the same leaf, and these two tentacles 
were inflected halfway towards the centre in 1 hr. 10m. ; 
all the many other tentacles round the same leaf re- 
maining motionless. The appearance of this one leaf 
showed in an unequivocal manner that these minute 
particles sufficed to cause the tentacles to bend. Alto- 
gether, ten such particles of hair were placed on ten 
glands on several leaves, and seven of them caused 
