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 Mankind.—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 the demonstration of the connection between insects and the propagation of yellow fever, malaria, and other disorders; and as an illustration 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 in the form of soil-inoculation, in the tracing of the sources of nitrates in the soil, and studies of the insects injurious to vegetation; their further application to practical forestry, and in sanitary sciences. This kind of research is also applied to the study of food-supply for fishes, as in the case of Plankton studies.
The Establishment and Maintenance of Biological Laboratories.—The establishment of seaside biological observatories and various other stations for research have had a great influence on the development of biology. The most famous biological station is that founded at Naples (Fig. 123) in 1872 by Anton Dohrn, and it is a gratification to biologists to know that he still remains its director. This international station for research has stimulated, and is at present stimulating, the growth of biology by providing the best conditions for carrying on researches and by the distribution of material which has been put up at the sea-coast by the most skilled preservators. There are many stations modeled after that at Naples. The Marine Biological Laboratory at Woods Holl, Mass., is of especial prominence, and the recently reorganized Wistar Institute of Anatomy at Philadelphia is making a feature of the promotion of anatomical researches, especially those connected with the anatomy of the nervous system.
Laboratories similar to those at the seaside have been established on several fresh-water lakes. The studies carried on in those places of the complete biology of lakes, taking into account the entire surroundings of organisms, are very interesting and important.
Fig. 123.—The Biological Station at Naples.