442 JOHN B WATSON 



I F 

 interval in Cuculus canorus is sometimes six to seven days. This 

 makes brooding almost impossible. Even the American cuckoo, 

 which builds its own nest, broods its own eggs and cares for its 

 own young, shows a strong tendency to lay eggs at irregular 

 intervals. Brooding is made possible, however, in the American 

 cuckoo, by the presence of a compensatory instinct in the young, 

 which, after a short stay in the nest, crawl out in the order in 

 which they were hatched, and pass through a climbing stage. 

 The reason for the disturbance in the reproductive cycle cannot 

 be stated, but it is probable that it is independent of food-habits. 



Herrick's three other papers "^ form the best discussion we 



have at the present time of instinctive action in birds. This 



valuable observational material ought to stimulate further 



experimental work of the type begun by Breed in the Harvard 



Laboratory. 



ORIENTATION 



Fish. Greene ^^' by means of an aluminum button attached 

 to the caudal fin, was able permanently to mark a number of 

 salmon entering the mouth of the Columbia River. By this 

 means the author hoped to study the length of time spent by 

 the fish in the tidewater regions after entering the mouth of the 

 river, and to determine the speed of individuals after the tidal 

 area had been passed. The success of the experiment depended 

 upon the fact that the commercial fisheries stationed along the 

 river would recapture the marked individuals, and return the 

 tag to the author. The aluminum button corrodes in salt water. 

 The length of time spent in the tidal regions could thus be approx- 

 imately gauged by the amount of corrosion showing on the button. 

 Fifty-nine fish were marked, and 17 retaken. The conclusion 

 arrived at by the author is that from 30 to 40 days were con- 

 sumed by the fish in crossing the tidal area (a much longer time 

 than was formerly supposed) ; and that once the fish had passed 

 the tidal area, they made the journey up the river at an average 

 speed of not less than seven and one-half miles a day. 



Victor Franz '^* maintains that fish have an extraordinarily 

 well developed sensitivity to differences in hydrographic con- 

 ditions. Currents are detected by means of the lateral line 

 organs; temperature, through the warm and cold corpuscles in 

 the skin; salinity, through the sense of taste; depth through 

 pressure and vision. The paper is a resume and not a report of 



