38 NATIONAL TRENDS IN BIOLOGY 



that the two sides, it may be the two eyes, ears, or nos- 

 trils, are equally stimulated" to secure a physiological 

 equilibrium. 



"Thus the young eel or elver goes straight upstream, 

 the male mosquito finds the buzzing female, and the moth 

 flies into the unnatural stimulus of the candle. Somewhat 

 higher is the persistent way in which newly hatched 

 loggerhead turtles make for the open horizon, as Profes- 

 sor G. H. Parker has shown, which usually and happily 

 means finding the sea."^ 



Finally, one may add the work done in comparative 

 psychology, and the attempt to show what effect the 

 ''mental" has had in determining the path of evolution. 



In this connection, also, should be mentioned the work 

 of Robert Chambers in developing a technique of micro- 

 scopic dissection, which opens up a field yet unexplored, 

 and that of Professor Pregl of Graz, who has done out- 

 standing work on the ultramicroscope and developed new 

 methods in microanalysis. 



From an agricultural point of view, a valuable answer 

 has been found for such questions as "How can we, even 

 by an importation of many different types of plants and 

 animals, each susceptible to differences in temperature, 

 clime, soil, moisture, and disease, keep that particular 

 balance in nature which modern transportation is continu- 

 ally upsetting, by importing with such plants and animals 

 those particular parasites, which will keep or again bring 

 back that particular balance in nature so much needed," 

 by the workers in applied entomology, well represented 



