70 



Mr. E. Ray Lankester on Haemoglobin, [Dec. 12, 



ever, be evaluated by the methods for the evaluation of vanishing frac- 

 tions. Y is clearly zero. X may be more readily obtained directly from 

 the expression for U. From that expression we find that for a single 

 circular current the attraction on such points is 



[ r 3 2 r 5 8 r 7 j 



Hence, in the case of a bobbin, if x be the distance of the attracted point 

 from O, the middle point of the axis of the bobbin, we have 



X f~/f M " , {■ * 3 «« 15 «« \ 



. ^ — 6 5 / — 3—7.4 2*\ 



+ , 



which gives X for points situated on the axis for which x is not less than 



December 12, 1872. 



WILLIAM SPOTTISWOODE, M.A., Treasurer and Vice- 

 President, in the Chair. 



Announcement was made from the Chair that the President had 

 appointed Dr. Sharpey a Vice-President. 



The Presents received were laid on the Table, and thanks ordered for 

 them. 



The following communications were read : — 



I. " A Contribution to the Knowledge of Hsemoglobin." By 

 E. Ray Lankester, M.A. Oxon., Fellow of Exeter College, 

 and Radcliffe Travelling Fellow of the University. Com- 

 municated by Prof. Huxley. Received July 29, 1872. 



The fact that exceedingly small quantities of Haemoglobin can be detected 

 with great facility by means of the microspectroscope, has rendered it 

 possible to trace the distribution of this important body among organisms 

 of various classes, and by comparing its absence from certain animals or 



