262 BOOKS AND CURRENT LITERATURE 



schools primarily we venture to say that because some minor topics 

 are stressed and genetics is not, herein is the weak spot. 



For a second or higher course in biology we esteem this work of 

 CKfton Hodge and Jean Dawson of very superior merit. Not only are 

 the specific subjects quite thorouglily treated but ample references 

 upon them are listed and secondary topics or problems outlined for the 

 advanced or ambitious student. Of new merit we would cite the dis- 

 cussion of planting home grounds, that of reforestation and the dis- 

 aster of deforestation, that of bird conservation and that of fish ''farm- 

 ing." The text is as well a laboratory guide for both teacher and 

 worker, giving as it does directions for the solving of its problems. Its 

 assistance in developing the "socialized" recitation and its dependence 

 upon projects make it a source of inspiration and commends it to pro- 

 gressive educators. 



Every teacher of biology, every physician, every minister, every 

 worker in community welfare and social service should possess the 

 book, and copies could well be accessible for supplementary reading in 

 the school and pubHc library. The diction and style render it readily 

 understood and the colored plates and numerous illustrations are 

 really illustrative. — Harold B. Shinn. 



Carbohydrate Metabolism of the Sweet Potato. — Recent experi- 

 ments reported from the Bureau of Plant Industry'^ appear to show 

 that free oxygen is not necessary to the formation of cane sugar. Sweet 

 potato roots were halved lengthwise, one half being immediately 

 analj^zed and the other used in the storage experiments. Sets of these 

 halves were subjected to air and oxygen at pressures greater than one 

 atmosphere; to air, oxygen and hydrogen at pressure of one atmos- 

 sphere; to air under a pressure of less than one atmosphere. The 

 experiments ran from three to twenty daj^s, and the temperature was 

 30°C., excepting one set of hydrogen experiments in which a tempera- 

 ture of 4.5°C. was used. Under pressures of 5 and 10 atmospheres 

 potatoes were killed, and analyses revealed shght hydrolysis of starch 

 and considerable hydrolysis of cane sugar, with increased concentra- 

 tion of reducing sugars. At atmospheric pressure and a temperature 

 of 30°C. starch hydrolysis and cane sugar formation went on in hydro- 

 gen as well as in oxygen and air, the highest percentage of cane sugar 



iHasselbring, Heinrich, Effect of Different Oxygen Pressures on the Car- 

 bohydrate Metabolism of the Sweet Potato. Journal Agricultural Research, 

 14:7. August, 1918. 



