Vol. LXX. No. 6. JUNE, 1907 



THE 



POPULAR SCIENCE 

 MONTHLY. 



EDITED BY J. McKEEK CATTELL 



CONTENTS 



The Problem of Age, Growth and Death : Professor Charles S. Minot 481 

 The Progress of Our Knowledge of the Flora of North America : Pro- 

 fessor Lucien Marcus Underwood i 497 



Notes on the Development of Telephone Service. Fred DeLand . . 1 18 



The Value of Science. M. H. Poincare £24 



The Acquisition of Language and its Relation to Thought. Dr. Alex. 



Hill 530 



Hygienic Requirements for the Printing of Books and Papers. Pro- 

 fessor Edmund B. Huey 542 



The Waste of Children. Dr. G. B. Mangold 549 



A Blazing Beach. Professor D. P. Penhallow 557 



The Progress of Science: » 



Lord Lister; The Centenary of the Birth of Louis Agassiz; Prevalence of the 



Plague in India; The Population of the United States; Scientific Items . . . 565 



Index to Volume LXX 577 



THE SCIENCE PRESS 



LANCASTER, PA. GARRISON, N. Y. 



NEW YORK: Sub-Station 84 

 Single Number, 30 Cents Yearly Subscription, $3.00 



Copyright, 1907, by THE SCIENCE PRESS 



