50 



It may be found eventually, say the men who worked out the 

 principle, that the animal organism, also, is capable of responding 

 to the stimulus of certain day lengths. They believe that the 

 migration of birds may be an illustration. Direct response to 

 such a stimulus, they say, is more in line with modern teachings 

 of biology than theories which assume that birds migrate as a 

 matter of instinct. 



PIN OAK IN NEBRASKA 



By Raymond J. Pool 



In a handbook of Nebraska trees published in March, 191 9, 

 I made the statement that: "Pin oak does not occur naturally in 

 Nebraska, but it occurs in north central Missouri and eastern 

 Kansas, so we may expect it to wander into our state some day 

 via the southeastern corner." The statement is rather inter- 

 esting in view of the fact that pin oak was discovered in south- 

 eastern Nebraska during the summer of 1919. 



Early in September, 1919, Mr. Thomas D. Howe, collector for 

 the department of botany in the University of Nebraska, col- 

 lected specimens from an oak tree growing near Table Rock, 

 Nebraska, and he believed that the tree was pin oak, Quercus 

 palustris Du Roi. Mr. Howe brought his specimens to the 

 department of botany where his earlier judgment was confirmed 

 by further study and comparison by several members of the 

 department. 



The tree in question is about 20 feet in height with a trunk 

 diameter of about 5 inches, breast high. It is growing in asso- 

 ciation with red oak at the edge of the natural oak woodlands on 

 the north-facing slope of a low hill about i}/2 miles northeast of 

 Table Rock. That town is in Pawnee county, about 35 miles 

 from the extreme southeastern corner of the state, but only 

 about 15 miles from the Kansas-Nebraska state line. 



The nearest house is a quarter of a mile from where the tree 

 stands on the edge of the forest where the forest gives way to 

 a cultivated field. It would seem very unlikely that anyone 

 could have planted the acorn in such a place; there would be no 



