July 16, 1920] 



SCIENCE 



51 



in Asia where maize is but little grown and 

 should not have come to light on the Amer- 

 ican Continent where maize is cultivated so 

 extensively and the varieties are so much 

 better known. 



If it is admitted that the waxy character 

 is the result of a single mutation then all 

 discussion of the time when it arose is of 

 course idle, for a single mutation may have 

 occurred as well at one time as another. 

 There still remains the peculiar distribution 

 of waxy endosperm and the differentation of 

 other characters as evidence of the antiquity 

 of the waxy mutation. The Shanghai variety 

 in which waxy endosperm was first discovered 

 possessed other peculiarities, the most con- 

 spicuous of these being erect leaf blades, 

 monostichous arrangement of the upper leaf 

 blades and an early development of silks 

 while the ear is still enclosed in the leaf 

 sheath. Unlike waxy endosperm, these char- 

 acters are not definitely alternative in inheri- 

 tence, but appear in varying degrees in crosses 

 with varieties not showing these character- 

 istics. 



Although the expression of all these plant 

 characters is variable even in the uncrossed 

 waxy strain, pure stocks of this variety always 

 present a distinctive appearance that imme- 

 diately separates them from any other variety. 

 It has been demonstrated that none of these 

 plant characters is correlated with endosperm 

 texture nor are any of them correlated with 

 one another. It is, therefore, not surprising 

 that the plants grown from the waxy seeds 

 from Upper Burma did not resemble the 

 Shanghai variety in any other particular. If 

 the view that the waxy maize of Shanghai 

 came originally from the region of the eastern 

 Himalayas be accepted, we must conclude that 

 sufficient time has elapsed since the intro- 

 duction for the Shanghai variety to acquire 

 its distinctive characters. 



In the light of our present knowledge this 

 unique character of an American plant ap- 

 pears to be confined to three isolated localities 

 in Asia. Unfortunately, nothing is known 

 regarding the maize varieties of Yunnan or 

 other points along the route from Burma to 



Shanghai. If the waxy character originated 

 in only one of these localities, however, it 

 would seem much more reasonable to assume 

 Burma as the region from which Shanghai 

 received the character than vice versa. This 

 is indicated by the inaccessibility of the r^ion 

 occupied by the HiU Tribes of Burma, the 

 specialized uses of the plant, and the exten- 

 sive series of named varieties. 



The finding of this peculiar type of endo- 

 sperm in the mountain region of Upi)er 

 Burma supports the idea that maize entered 

 China from the west instead of the east. 

 This is in accord with the early Chinese ac- 

 counts of maize as presented by Dr. Laufer. 

 A more thorough knowledge of the maize 

 varieties of the Himalayan regions promises 

 to be the key to the distribution of maize in 

 Asia. 



G. IST. Collins 



Bureau of Plant Industry, 

 Department of Agriculture 



PHYSICAL MEASUREMENTS IN PSY- 

 CHOLOGY 



The recent article by Dr. Paul E. Klopsteg^ 

 on physical methods and measurements and 

 the obligation of physics to other sciences, 

 carries a strong appeal for those psychologists 

 who are obliged to prepare students for re- 

 search in the investigations of human be- 

 havior. The specialization found in the psy- 

 chological laboratories is often merely due to 

 the development of a special technique in 

 physical measurements suited to a whole 

 series of problems, rather than to a restricted 

 psychological interest. Eeeent progress in 

 psychological methods demonstrates very 

 clearly that every problem dealing with the 

 fundamental aspects of human behavior is 

 also partly a physical problem. Much of the 

 apparatus used in making measurements is 

 " home-made " and while good results have 

 been secured, it is equally true that better 

 experimental results would be secured and 

 much time saved if some expert in physical 

 measurements, who is also interested in the 



1 Science, April 16, 1920, N. S., 51, 384-386. 



