RECENT TENDENCIES IN BIOLOGY 443 
Anatomy of the Nervous System.—In another direction 
the progress of anatomical studies is very evident, that is, 
investigations of the nervous system and the sense-organs. 
The wonderfully complicated relations of nerve elements 
have been worked out by Ramon y Cajal. The studies of 
Hodge and others upon optical changes occurring within the 
cells of the nervous system owing to their functional activity 
have opened a great field for investigation. The studies of 
Strong, Herrick, and others upon the distribution of nerve- 
components in the nerves of the head and the investigations 
of Harrison on the growth and the regeneration of nerve- 
fibers give illustrations of current tendencies in biological 
investigation. The analysis of the central nervous system 
into segmental divisions on the basis of functional activity 
(Johnston) is still another illustration. 
The Application of Biological Facts to the Benefit of Man- 
kind.—The practical application of biology to the benefit 
of mankind is a striking feature of present-day tendencies. 
The activity set on foot by the researches of Pasteur, Koch, 
and others has created a department of technical biology of 
the greatest importance to the human race. 
Under the general heading should be included tne demon- 
stration of the connection between insects and the propagation 
of yellow fever, malaria, and other disorders; and as an illus- 
tration of activity in 1907, we think of the commission recently 
appointed to investigate the terrible scourge of the sleeping- 
sickness which has been prevalent in Africa. Here also we 
would group studies of a pathological character on blood- 
immunity, toxin and antitoxin, also studies on the inoculation 
for the prevention of various diseases that affect animals and 
mankind. Very much benefit has already accrued from the 
practical application of biological researches of this nature, 
which, in reality, are still in their infancy. 
We find the application of biological facts to agriculture 
