216 



SCIENCE 



[N. S. Vol. XXVI. No. 659 



(0.003 per cent.)," i. e., of magnesium sulphate 

 (anhydrous, 0.00147 per cent.). 



4. It is a well-known fact that many compounds 

 that act poisonously at a certain concentration 

 can act in very high dilution as stimulants of 

 growth. 



Miss Burlingham said nothing to the con- 

 trary. She found nothing in opposition to it.. 

 There is nothing in her abstract to warrant 

 the inference that she was not aware of this 

 " well-known fact." 



5. It is erroneous to attribute this stimulating 

 action to any nutritive quality of the poison. 



Miss Burlingham did not " attribute this 

 stimulating action to any nutritive quality of 

 the poison." She said her results " show con- 

 clusively that magnesium sulphate in proper 

 dilution is beneficial to the growth of seed- 

 lings." She did not offer any explanation of 

 her preliminary results, merely stated them. 



It is ridiculous for Professor Loew to as- 

 sume that Miss Burlingham exhibited preju' 

 dice in her abstract, for neither she nor I had 

 any preconceived notions to establish, nor any 

 theories to maintain. Her conclusions were 

 drawn impartially from her results. 



Professor Loew concluded his letter with 

 the following unbiased allusion: 



6. The unprejudiced reader who desires some in- 

 formation as to the nutritive role of magnesium 

 salts in plants and to the conditions under which 

 this function can be performed, is kindly requested 

 to consult Bulletin No. 45 of the Bureau of Plant 

 Industry, "The Physiological Role of Mineral 

 Nutrients in Plants," Washington, 1903. 



I cheerfully commend " Bulletin No. 4.5," of 

 which Professor Loew is the author, to the 

 attention of any one wishing " information 

 as to th^ nutritive role of magnesium salts in 

 plants and to the conditions under which this 

 function can be performed." The said bul- 

 letin is the most valuable single contribution 

 to our knowledge of the questions discussed 

 in it, and reflects brightly the flood of light 

 that Professor Loew has thrown upon the 

 subject since he undertook its investigation. 

 Nevertheless the "unprejudiced reader" of it 

 will certainly conclude, after studying " Bul- 

 letin No. 45," that there is probably very much 



more for all of us, including Professor Loew, 

 to learn about the " nutritive role of magne- 

 sium salts in plants " and " on the conditions 

 under which this function can be performed." 

 The " unprejudiced reader " will also surely 

 welcome such earnest attempts as Miss Bur- 

 lingham's to extend our information on de- 

 tails of the subject. 



Miss Burlingham's preliminary paper ap- 

 peared in the July number of the Journal of 

 the American Chemical Society. It gives the 

 data upon which were based the remarks in 

 her abstract that Professor Loew has misin- 

 terpreted for the " unprejudiced reader." It 

 makes further comment here unnecessary. 



William J. Gies 

 New York Botanical Gabden 



a note on certain widely distributed 



LEAFHOPPERS (HEMIPTERa) 



Certain leafhoppers have more or less re- 

 cently become notorious for the damage they 

 occasion to various cereals, such as sugar-cane 

 and sorghum. PerMnsiella saccharicida (Kir- 

 kaldy) has done much damage in Hawaii, 

 having been introduced from Queensland, 

 where, however, it is not native. It is to be 

 found wherever sugar-cane is grown in Aus- 

 tralia and Hawaii, and I have recently re- 

 ceived it from Java. Peregrinus maidin 

 (Ashmead) was described from maize in 

 Florida and is now widely distributed over 

 the southern United States; it has an even 

 wider range now than PerkinsieUa sacchari- 

 cida, for it is all through eastern Australia, 

 Hawaii, Viti and, I think, Java,, while Mr. 

 Distant has recently redescribed it as Punda- 

 luoya simplicia from Ceylon. 



G. W. KiRKALDY 



I 



SPECIAL ARTICLES 



COLOR inheritance AND SEX INHERITANCE IN 



CERTAIN APHIDS 



The color changes that occur in the sexual 

 generation of certain aphids, and the correla- 

 tion of a definite color with each sex, have 

 suggested that these insects may furnish 

 favorable material for testing the possibility 



