24 ORGANIC BEHAVIOUR 
system, the ramifications of which are not less perfect, that 
one of the larger and higher animals is knit together into 
an organic whole. The former carries to the cell the raw 
materials for the elaboration of its explosive products, and, 
after the explosions, carries off the waste products which result 
therefrom. The nerve-fibres carry the stimuli by which the 
explosive is fired, while the central nervous system organizes, 
co-ordinates, and controls the explosions, and initiates the 
elaboration of the explosive compounds. Blood and nerves 
co-operate to render corporate behaviour possible. 
IV.—THE BEHAVIOUR OF PLANTS 
A short parenthetic section on the behaviour of plants may 
serve further to illustrate the nature of organic behaviour. 
We have seen that Paramecium is apparently attracted by 
faintly acid solutions, and have briefly considered Dr. Jennings’s 
interpretation of the facts disclosed by careful observation. 
In the ferns the female element, or ovum, is contained in a 
minute flask-shaped structure (archegonium), in the neck and 
mouth of which mucilaginous matter, with a slightly acid 
reaction, is developed ; and this is said to exercise an attractive 
influence on the freely swimming ciliated male elements, or 
spermatozoids, which are necessary for fertilization. ‘* Now, 
it has been shown by experiment that the spermatozoids of 
ferns are attracted by certain chemical substances, and especially 
by malic acid. If artificial archegonia are prepared (consisting 
of tiny capillary glass-tubes) and filled with mucilage to which 
a small quantity of this acid has been added, they are found, 
when placed in water containing fern-spermatozoids, to exercise 
the same attraction upon them which the real archegonia 
exercise in nature. The malic acid gradually diffuses out into 
the water, and the spermatozoids are influenced by it, so that 
they move in the direction in which the substance is more 
concentrated, 7.e, towards the tube. Although it cannot be 
proved that the archegonia themselves contain malic acid, as 
they are too small for a recognizable quantity to be obtained 
