SCIENCE 



Friday, August 31, 1917 



CONTENTS 

 Liehig's Law of the Minimum in relation to 

 General Biological Problems: Professor 

 ' Henry D. Hooker, Jr 197 



The Peck Testimonial Exhibit of Mushroom 

 Models: H. D. House 204 



Scientific Events: — 

 Farm Colonies for Tuberculous Soldiers; 

 Besearch Work of the Bed Cross in France; 

 War Demonstration Hospital of the Bocke- 

 feller Institute; The Mathematical Asso- 

 ciation of America; John Oren Beed and 

 Karl E. Guthe 205 



Scientific Notes and News 208 



University and Educational News 210 



Discussion and Correspondence: — 



The Interpretation of the Besults of Field 

 Experiments with Different Phosphates: 

 Professor C. A. Mooers. A Method for 

 obtaining Amceba: C. B. Gordon. Crossing 

 over in the Sex Chromosome of the Male 

 Fowl: Dr. H. D. GooDAiE. Tli£ Equal 

 Parallax Curve for Frontal and Lateral 

 Vision: Paul E. Eider. A Predecessor of 

 Priestley : Db. W. W. Keen 210 



Scientific Books: — 

 Kelsey on the Physical Basis of Society: 

 PROrEssoR P. Stuakt Chapin. Licks on 

 Becreations in Mathematics: Professor 

 Louis C. Karfinski 215 



Special Articles: — 

 The Effects of Thyroid Removal upon the 

 Development of the Gonads in the Larvw 

 of Bona Pipiens: Professor Bennet M. 

 Allen. The Staiisiphon: Professor P. B. 

 Perkins 216 



The American Philosophical Society: Pro- 

 fessor Arthub W. Goodspeed 219 



MSS. Intended for publication and boots, etc.. Intended for 

 review should be sent to Professor J. lIcKeea Cattell, Ganison- 

 On-Hudson. N. Y. 



LIEBIG'S LAW OF THE MINIMUM IN 

 RELATION TO GENERAL BIOLOG- 

 ICAL PROBLEMS 1 



The Law of the Minimum has never been 

 accurately defined, although the idea that it 

 involves is relatively simple. Professor B. 

 B. Livingston says in a recent paper^ that 

 "this principle is still quite incomplete log- 

 ically and its statement will assuredly be- 

 come much more complex as our science 

 advances." In order to get a clear under- 

 standing of the law so that it may be stated 

 accurately, we will begin with a simple 

 application to chemical reactions. 



One molecule of KOH reacts with one 

 molecule of HCl to form one molecule of 

 KCl and one of H^O. If only one molecule 

 of KOH is present, only one molecule of 

 KCl can be formed, no matter how many 

 molecules of HCl are present ; and likewise 

 if only one molecule of HCl is present, only 

 one molecule of KCl can be formed, no mat- 

 ter how many molecules of KOH are pres- 

 ent. By considering the weights of the 

 reacting substances, the situation is some- 

 what complicated: 56.1 grams of KOH 

 react with 36.5 grams of HCl to form 74.6 

 grams of KCl and 18 grams of H^O. In 

 round numbers 3 parts by weight of KOH 

 and two of HCl give 4 parts by weight of 

 KCl and one of H,0 : 3/4 gr. of KOH and 

 1/2 gr. of HCl are necessary to form a gram 

 of KCl. Let us call these fractions, 3/4 and 

 1/2, the specific reactive weights of KOH 

 and HCl in respect to the formation of a 

 unit quantity of KCl. Suppose x amount 

 of KOH and y of HCl are given. If x and 



1 Paper read before the Biological Club of Yale 

 University, April 19, 1917. 



2 Plant World, 20: 1-15, 1917. 



