Jantjabt 15, 1915] 



SCIENCE 



99 



found recently in a gravel pit in Pony Hollow, 

 twelve miles southwest of Ithaca, N. T., on the 

 property of Mr. Bert Drake. Unlike most 

 Mastodon finds from this region this is not 

 postglacial. It was found in place twenty-four 

 feet below the surface in stratified sand and 

 gravel which was being used in good roads 

 work. The pit is in the base of an extensive 

 terrace whose top follows the valley wall high 

 above the outwash gravel plain which occu- 

 pies the fioor of the valley. The exact origin 

 of this Pleistocene terrace is obscure but it is 

 certainly not later than the end of the ice 

 occupation of the valley and may be earlier. 



The tusk was broken in removing the gravel. 

 Two pieces, each about a foot long, from ten 

 to thirteen inches in circumference, were pre- 

 sented to the Paleontological Museum of Cor- 

 nell by E. A. Dahmen, the road engineer. 

 Three approximate measurements of the cur- 

 vature of the tusk gave from two feet one inch 

 to two feet eleven inches as the radius of 

 curvature. 



Pearl Sheldon 



Cornell University 



SCIENTIFIC BOOKS 



THE TRANSLOCATION OF MATERIAL IN DYING 

 LEAVES ^ 



The fact of an autumnal transfer of nu- 

 trient matter from leaves was first clearly 

 stated by Sachs, in 1863. Sachs's statement 

 was based on microscopical examinations of 

 the leaves of a series of plants in various stages 

 of their autumnal changes, whereby he deter- 

 mined that starch and chlorophyll disappeared 

 from leaves before their fall. He extended 

 this observation to cover most of the other nu- 

 trient materials in the leaf. Swart, however, 

 holds that the solution of this question in its 

 broader sense is to be had only by chemical 

 analyses such as he has made. 



According to Swart, the first essential to a 

 correct answer is a correct wording of the prob- 

 lem, as follows : 



1 Swart, Dr. Nicolas, "Die StofEwanderung in 

 ablebenden Blattern," pp. 1-118, Taf. 5, Jena, 

 Verlag von Gustav Fiseher, 1914. 



During the autumnal coloring of leaves ca.n. 

 there be determined, by chemical analysis, a trans- 

 location of nutrient materials during the period 

 extending from shortly before to directly after the 

 close of the yellowing? 



It is essential to draw the time limits thus 

 sharply, since this period represents a sharply 

 limited, externally recognizable terminal pe- 

 riod in the life of the leaf, which in addition 

 to anatomical variations in the petiole, may be 

 directly recognized by the physiological proc- 

 esses which are indicated to us by the disap- 

 pearance of the chlorophyll. If we would an- 

 swer the question as to whether, before the fall 

 of the leaf, there may be demonstrated a trans- 

 fer of any substances, it is necessary to regard 

 only the period during which the leaf, as indi- 

 cated by these externally recognizable proc- 

 esses, prepares for its final act. After answer- 

 ing this narrower question, then we should 

 consider the amount of these materials in the 

 leaf at other periods of the year, in order to 

 arrive at a causal explanation of the phenom- 

 ena. 



The necessary chemical analyses fall into 

 two groups : those which extend over the entire 

 vegetative period of the leaves, and those 

 which cover only the period directly before 

 and after yellowing. In most of the former 

 investigations the leaves analyzed began to be 

 removed from the tree at a late period, but 

 quite independent of the exact time when the 

 coloring began and ended. The value of the 

 results of such analyses must, therefore, be 

 estimated with caution since, even in most 

 favorable eases, they can only give us an an- 

 swer to the question of whether, in general, yel- 

 low leaves are poorer in their content of any 

 given substance than green leaves of any 

 earlier period. Thus a maximum or a mini- 

 mum in the proportion of the given material 

 in the intervening period would give results 

 entirely misleading with reference to the ques- 

 tion whose answer is sought. 



Another objection to former researches that 

 extend over the entire vegetative period is that 

 very frequently a large number of leaves for 

 study were taken at one time from the same 



