238 Scientific Proceedings^ Royal Dublin Society. 



a later date undissolved bodies were successfully removed by centrifuging 

 at a speed of 9,000 revolutions per minute, so that these determinations can 

 now be readily made. 



So far the highest mean molecular weiglit obtained in Ilex is 300, viz. 

 in the mature leaves of the antepenultimate growth, October 24, 1910. The 

 highest previously obtained for leaves were 273 for Si/rinc/a vulgaris and 280 

 for Eucalyptus globulus. The lowest for the leaves of Ilex was furnished by 

 mature leaves, February 26, 1910, viz. 215. 



Generally the mean molecular weiglit of the dissolved substances in the 

 roots is below these extremes, viz. 180-208 ; but in the sap of the roots, 

 October 5, 1910, the mean molecular weight of the dissolved matter was 

 determined at 254. The mean molecular weight of the dissolved substances 

 in the roots of Syringa vulgaris has already been found to vary between 178 

 and 254. The latter figure was determined on a sample gathered October 23, 

 1909. 



