20 Mr Griffiths and Mr Glarh, On the rise in resistance [Nov, 28, 



flowers in various Labiatae {Ne'peta Glechoma, Thymus serpyllum, 

 and Galeopsis Tetrahit), and points out that in nearly all the cases 

 he observed, the abortion took place in a symmetrical way, i.e. the 

 abnormal flowers were either female, or had lost two stamens, and 

 those either the two posterior or the two anterior. The observa- 

 tions of 1890 — 91 on hermaphrodite plants have therefore been 

 analysed carefully, and it has been found that on the whole this 

 statement is correct. Out of 265 abnormal flowers, 179 had the 

 abortion symmetrical. Of these, 142 were female, 26 had the 

 two anterior (long) stamens missing, and 11 the two posterior 

 (short). It was noticed that the long anterior stamens were more 

 often aborted than the short posterior ones. 



It is hoped to publish a paper after the conclusion of these 

 observations, giving full details, and also a general discussion of 

 the subject of gynodioecism, with the various theories concerning 

 it that have from time to time been proposed. These will be 

 tested so far as possible, in the course of the experiments now 

 being carried on. 



In conclusion, the author's warmest thanks are due to Mr 

 Francis Darwin, for the constant advice and assistance he has 

 given throughout the work, and to Mr W. French, who kindly 

 undertook some of the observations during the author's absence, 

 in Sept. 1891. 



November 28, 1892. 



Peof. T. M K. Hughes, President, in the Chair. 



The following communications were made : 



(1) On the rise in resistance of a Conductor when trans- 

 mitting a Current. By E. H. Griffiths, M.A., Sidney College, 

 and G. M. Clark, B.A., Sidney College. 



As "we mentioned in a paper which we had the honour to 

 read before this Society "On the Measurement of Low Tempera- 

 ture," we have for a long time suspected that the heating effects 

 of small currents necessary to determine a resistance are of more 

 importance than is usually supposed. As these might be sufficient 

 to account for the differences which have occurred m the measure- 

 ment of the same resistance-coil by different observers, we have 

 thought it advisable to bring before the Society a description 

 of the means we adopted to overcome this difficulty when it 

 presented itself to us, in an exaggerated extent, in our deter- 

 mination of the mechanical equivalent of the heat developed 

 by an electric current. In these experiments the heat being 



Eigenschaften hybrider u. gynodiocischer Pflanzen." Engler's Botan. Jahrbuch iv. 

 1883, p. 189. 



