Sense-Life and Sensibility 
which cannot be reconciled with that theory. He 
used a knife with a triangular point similar to that used 
by oculists in operations for cataract, and by means of 
it removed the whole epidermis of a Mahonia stamen 
without even detaching it from the flower.” As these 
skinned stamens still moved when touched, it is clear 
that more than the epidermis is concerned. As M. 
Dop found that such stamens on movement showed the 
same electrical reaction that occur when animal muscle 
contracts, it is more probable that it is the protoplasm 
which contracts or is in some way “distressed” on 
stimulation. 
Another remarkable power of plant protoplasm is 
chemotropism, or the recognition of different substances 
which may attract or repel motile plants such as 
bacteria or spores. One may compare this to “taste” 
in the higher animals (not of course literally). One 
interesting experiment is as follows: a quantity of the 
actively moving male cells or antherozoids of both a 
moss and a fern are placed in water and then two 
vaccine tubes are introduced, filled, the one with a weak 
solution of cane-sugar and the other with malicacid. The 
moss sperm cells will collect in the cane-sugar and those 
of the fern in the malic acid. But if these solutions are 
too strong, the sperm cells not only refuse to be attracted 
but are actually repulsed and swim away from them.% 
Bacilli can detect and react to .oor per cent. solutions 
of certain salts, concentrations so weak, that is to say, 
that no human being could detect them. Some other 
very interesting comparisons of their tasting powers 
have been described by the same author.’* Nor is this 
power confined to moving spores of algz and to bacteria, 
Roots show the same power of turning towards or 
away from certain substances. Roots of Leguminosz 
will, for instance, turn and grow towards phosphates, but 
149 
