October 12, 1917] 



SCIENCE 



369 



which had been treated with 0.1 KCISr and 

 then with water. The solution was allowed 

 to stand until it became concentrated by 

 evaporation: it then appeared black. It was 

 found that where the nuclei had been squeezed 

 out of the cut cells by the knife they had 

 taken up some stain but not more than the 

 cytoplasm. In cells which were merely cut 

 open there was little or no staining. 



We must therefore conclude that oxida- 

 tion occurs more rapidly in the nucleus than 

 elsewhere in the cell. The only way to es- 

 cape this conclusion would be by assuming 

 that at the moment of injury there is a sud- 

 den migration into the nucleus of some or all 

 of the substances necessary for the oxidation. 

 This is not only very improbable from a theo- 

 retical standpoint, but observation shows that 

 it can not be the case, for in tliis migration 

 the substances would mingle and produce the 

 pigment either outside the nucleus, or at its 

 surface, before any pigment appeared in the 

 interior of the nucleus. Observation of the 

 nucleus shows that the pigment appears as 

 soon within the nucleus as at its surface. 



We may therefore conclude that the sub- 

 stances necessary for oxidation do not sud- 

 denly migrate into the nucleus at the moment 

 of injury but that they must exist there before 

 the cell is injured. 



We may ask why the nucleus does not be- 

 come darkened in the normal condition of the 

 cell. The investigation of several workers 

 have made it probable that the pigments pro- 

 duced by oxidation under normal conditions 

 are at once reduced, giving up their oxygen 

 to other substances in the cell. When injury 

 occvirs the reduction is checked more than the 

 oxidation, with the result that the pigment 

 accumulates. 



It is also probable that in many cases the 

 injury brings the cells into contact with more 

 oxygen than under normal conditions. 



In order to compare these results with those 

 produced by the indophenol reagent, leaves 

 were placed in a mixture of equal parts of 

 alpha naphthol (saturated aqueous solution) 

 and para phenylene diamine (1 per cent, 

 aqueous solution). If the reagents are freshly 



made up there is little action, but if they have 

 stood long enough to take up oxygen or if 

 H,0, is added a purple color develops in the 

 cells, which eventually becomes deeper in the 

 nucleus. The result depends greatly on the 

 condition of the reagent and the rate at which 

 it penetrates the tissue. 



The general conclusion is that while the 

 indophenol reaction indicates that the nucleus 

 is the center of oxidation it does not give as 

 definite information on this point as does the 

 formation of natural pigments within the cell 

 resulting from the oxidation of substances 

 normally present. 



SUMMARY 



Injury produces in the leaf-cells of the In- 

 dian Pipe (Monotropa uniflora) a darkening 

 which is due to oxidation. The oxidation is 

 much more rapid in the nucleus than in the 

 cytoplasm and the facts indicate that this is 

 also the case with the oxidation of the un- 

 injured cell. W. J. V. OSTERHOUT 



Laboratory of Plant Physiology, 

 Harvard University 



SOCIETIES AND ACADEMIES 



AMERICAN MATHEMATICAL SOCIETY 

 At the invitation of Adelbert College and the 

 Case School of Applied Science, Cleveland, Ohio, 

 the twenty-fourth summer meeting of the Ameri- 

 can Mathematical Society was held at these insti- 

 tutions on Tuesday, Wednesday and Thursday, 

 September 4^6, 1917. This was the society's sec- 

 ond visit to Cleveland, the annual meeting having 

 been held there in the winter of 1912-1913. On 

 the present occasion the interest was reinforced by 

 the meeting of the Mathematical Association of 

 America, immediately following on September 6-7. 

 The arrangements, which were in charge of a com- 

 mittee representing both organizations, included a 

 joint session on Thursday morning, at which Pro- 

 fessor L. P. Eisenhart presented an address on 

 "Darboux's contribution to geometry," and a 

 joint dinner on Wednesday evening, attended by 

 seventy-six members and friends, to whom Presi- 

 dent Thwing, of Western Eeserve University, spoke 

 a word of welcome, which was followed by a num- 

 ber of informal responses to the calls of the toast- 

 master. Professor E. V. Huntington. The pro- 

 gram on Wednesday afternoon included an in- 

 spection of the harmonic analysis apparatus of 



