282 Mr Philip Sewell on the [sess. 



Gaxitier, Hoppe-Seyler, and Hansen. 



C = 73-97 73-4 68-3 



H = 9-8 9-7 10-5 



N = 415 5-62 5-1 



O = 10-33 9-57 16-9 

 Ash (Phospliates) 1-75 



In reference to the percentages of carlwn and nitrogen, it 

 is of interest to note that Sachsse, who showed that the 

 nieml)ers of his green series contained nitrogen while the 

 others had none, is supported hy Professor Gilbert, in a 

 communication made at the last British Association meeting 

 in Aberdeen. He pointed out that an increase in the depth 

 of green colour is not associated with a relatively high 

 carbon percentage, but depends directly on the amount of 

 nitrogen present in the plant. 



All chemists aie agreed that iron cannot be detected in 

 the composition of chlorophyll, though Timiriazeff has again 

 suggested that all the conditions of chlorophyll and its 

 various reactions would Ije explained by the assmnption that 

 iron in the form of an FeOFcO^ compound is present. All 

 that is yet certain is, tlic necessity of iron for its pro- 

 duction. 



Certain of the allied or derived colours of the leaf, as for 

 instance carotin (C^gH^^O of Arnaud), have been selected for 

 observation with more or less satisfactory results ; but of the 

 blue, red, and fluid yellow colours of flowers, Flahault says 

 " the most prominent character of the many they share in 

 common is the exceptional readiness with which they are 

 changed and Inoken down under the greater number of 

 reagents." 



A connection ])etween red in leaf and flower is evidenced, 

 according to Professor Schnetzler, l)y the fact that tannin 

 occurs more plentifully where such colour is present, either 

 in flowers or in young leaves. 



.Mlhough many botanists regard the Ihiid colours — red, blue, 

 or yellow — as derivatives of chlorophyll, Vines states that " as 

 yet there is no direct proof that they are derivatives." From 

 the researches of Sehim})er, mentioned al»ove, it is evident 

 that, in tlit; words of I'rofessor Marshall Ward, we have a 

 "genetic and lh('i(;fore leal relationshij) " between green and 



