The Mid-Winter Meetings. 197 



osprey's nest in the fall is in the nature of repairs, although it answers this purpose 

 admirably. The nest is built because the bird is at the opening of a new cycle, and 

 is impelled by the building instinct. 



Many confirmatory facts could be given. The herring gull will not only bury 

 an egg, in rebuilding on its old site the nest, when its cycle has been interrupted by 

 fear, but will bury its dead young which it treats as so much nesting material. 



The Interrelation of Sensory Stimulations in Amphioxus. By G. H. Parker, 

 Harvard University. 



To weak acid solutions and other like mixtures the anterior end of Amphioxus 

 was found to be most sensitive, the posterior end less so, and the middle trunk 

 region least sensitive. To the pressure of a camel's hair brush, the middle region was 

 less sensitive than the two ends which, however, were not distinguishable one from 

 the other by this method of stimulation. To a current of warm water (40° C.) the 

 anterior end was most sensitive, the middle less, and the posterior end least. There 

 were no reactions to a current of cold water (2° C.) To a fine pencil of strong sun- 

 light, previously passed through water to eliminate heat, the anterior end including 

 the "eye spot" was not sensitive, the region immediately behind the "eye spot" 

 was most sensitive, the posterior region slightly less so, and the middle region least 

 so. 



The distribution of sensitiveness to light corresponds to the distribution of the 

 pigment cups in the central nervous organ and these cups are without doubt the 

 mechanisms concerned with the reception of light. The distributions of the other 

 classes of sensitiveness are in mutual agreement, and, from the nature of their 

 stimuli, these classes are doubtless represented by integumentary nerve terminals. 

 To what extent these classes are independent may be inferred through the effects of 

 exhaustion. After the tail of Amphioxus has been repeatedly stimulated with weak 

 acid, the animal ceases to respond to this stimulus but is still normally sensitive in 

 that part of its body to heat or to mechanical stimulation. In a similar way after 

 exhaustion to mechanical stimulation or to heat stimulation, the particular part of 

 the body experimented upon is still sensitive to the other classes of stimuli. Exhaus- 

 tion to light stimulation has no effect upon the sensitiveness to the other classes of 

 stimuli. These observations lead to the conclusion that light, heat, mechanical and 

 chemical stimuli are received by physiologically separate mechanisms and that 

 these mechanisms are located in the skin except in the case of light, whose receptive 

 organs are the pigment cups in the central nervous organ. 



The Habits and Life History of Cryptobranchus allegheniensis. By Bertram 

 G. Smith. (Introduced by Dr. O. C. Glaser.) 



The adult Cryptobranchus has its dwelling place in a cavity or cavern under a 

 large rock, in swift and shallow water. The animal seldom comes out during the 

 daytime, except during the breeding season. The eggs are laid and fertilized during 

 the first two weeks of September. They are deposited in the usual dwelling-place 

 of the animal. About 450 eggs are laid by a single female. Fertilization is external 

 as in fishes; no spermatophores are formed. After the eggs are deposited they are 

 usually guarded for a time by the male, who fights and drives away other hell- 

 benders which attempt to eat the eggs. The male himself eats some of the eggs, but 

 on account of the slowness of his digestion is unable to eat more than a small pro- 

 portion, hence his presence is in the main protective. In defending the eggs the 



