July 4, 1913] 



SCIENCE 



25 



listed in 1824, there is found a plate showing 

 one of the pods produced by Mr. Seton. This 

 colored plate shows two green peas and three 

 white ones in the same pod. 



It is interesting to note how close these 

 men came, in the year of his nativity, to the 

 law which later made Mendel famous. 



T. H. McHatton 



College of Ageiculture, 

 University of Georgia 



the food of plants 



Dr. Benedict in a recent number of Science 

 opens the question regarding the definition of 

 the word food as used by botanists. 



That we need to come to some agreement is, 

 I think, generally felt by teachers in all grades 

 of the subject. 



If we have in mind the plant's relation to 

 substances outside of itself which may be 

 taken and used in any of its vital processes, 

 then carbon dioxide, water and minerals are 

 food. This notion was suggested by the ani- 

 mal organism, which, however, is essentially 

 unlike a plant in respect to immediate ex- 

 ternal relations. The term plant food arose 

 to emphasize the importance of certain min- 

 eral constituents of the soil. Its use ignores 

 the green plant's unique place in nature, and 

 by implication even denies it. 



If on the other hand we have reference to 

 growth and repair of living tissue, carbon 

 dioxide, water and minerals are waste prod- 

 ucts, the antithesis of food. 



The question resolves itseK into this, to 

 which concept of the plant's activities is the 

 concept food most nearly related? If the 

 answer is nutrition then only such substances 

 as can be oxidized in the tissues and energy 

 thereby set free, are foods. To answer the 

 question otherwise is not only to invite trouble 

 from such a term as reserve food, but worse, 

 make the whole subject of metabolism impos- 

 sible of presentation. If we write the words 

 " energy stored " and " energy set free " in 

 the equations for photosynthesis and for res- 

 piration, the term food, in its commonly ac- 

 cepted sense is clear, and the term as applied 

 to inorganic matter an absurdity. Neverthe- 



less, the term plant food as applied to nitrate 

 of soda, etc., is with us to stay, just as surely 

 as oysters will continue to be known as shell- 

 fish. 



It is our business to fit pedagogic methods 

 to the facts and see that fundamental truths 

 are clearly set forth regardless of how many 

 qualifying terms we must employ. 



I forbear quoting sentences from text-books 

 in which the term food is used in opposite 

 senses without explanation, thus by implica- 

 tion denying the importance of photosynthesis 

 and ignoring the law of conservation of en- 

 ergy. Hypercritieism is born of pedantry, 

 but consistency is a jewel. The agriculturist 

 can not use our term fruit and we can not use 

 his term plant food vnthout contradiction and 

 confusion. The trouble is not so much one of 

 definition as of usage. A Frenchman who 

 was learning English said : " When a horse 

 goes rapidly you say he is fast, and when you 

 tie him to the post he is fast. Your language 

 is very difficult." 



H. N. Conser 



University of Maine, 

 May 27, 1913 



A GOOD soil tube 



Glass tubes are generally used in soil phys- 

 ics laboratories when carrying on experi- 

 ments on capillary rise and distribution of 

 water in soils. To give the best results these 

 must be one and one half to two inches in 

 diameter, and are expensive and fragile. In 

 student laboratories with class numbering 

 100 or more the writer has had an annual 

 breakage of over 75 per cent. 



During the past year a new style of tube 

 has been used in the soil technology labora- 

 tories at the University of California. This 

 form was suggested to the writer by Professor 

 E. O. Fippin, of Cornell, and is in use there 

 and in other laboratories. 



The tubes consist of a wire-mesh cylinder, 

 two inches in diameter and of the desired 

 length, made by wrapping one fourth inch 

 mesh wire netting around a form and riveting 

 the edges at intervals of six or eight inches. 

 Celluloid tubes made of thin transparent sheet 



