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 wonderfuHy comphcated 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 ner\'ous 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 ])y 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 



