Leaves from tJie Ship Canal. 233 



parent substance. Its solutions may be exposed to air and 

 light for a considerable time without undergoing much 

 change, whereas solutions of normal chlorophyll, on ex- 

 posure to the same combined agency, are rapidly bleached, 

 with entire destruction of the colouring matter. The cir- 

 cumstance of the chlorophyll having undergone modification 

 in the leaves of the deposit may serve to explain its 

 continued presence after the long period during which it is 

 said these leaves have lain buried. Still the fact of its 

 remaining unchanged for so long a time, even in the modified 

 state, is sufficiently remarkable, and can only be explained 

 by supposing that the leaves were suddenly and completely 

 buried under a mass of material which to a great extent 

 preserved them from the action of light and air. It is 

 worthy of remark that the leaves of the deposit are com- 

 paratively poor in colouring matter, yielding far less than 

 the same quantity of fresh leaves would do. 



