i']6 Appendix. 



]VI. 



EXPERIMENT TO SHOW THAT CHLOROPHYLL 



BODIES MIGRATE UNDER THE INFLUENCE 



OF VARYING INTENSITIES OF LIGHT. 



BY V. M. SPALDING. 



If we make a thin section of a green leaf from a tree or 

 flowering plant, or, better still, if we select a fresh, delicate leaf 

 from a clump of growing moss, and subject it to examination 

 with the microscope, it will be seen that, like nearly all other 

 plant tissue, the leaf is made up of distinct cells. To consider a 

 special case at once, it will be well to notice the structure of the 

 leaf employed in the experiment, which belonged to a common 

 species of moss, Muniiwi affiiie. 



The leaf is very snvall, not more than one-fifth of an inch 

 long and about two-thirds as wide. It is very delicate, almost 

 transparent, and can be examined under the microscope without 

 any preparation whatever. Thus examined, its structure is seen 

 to be exceedingly simple. It is made up of a single layer of 

 cells, except along the midrib, where it is two or three layers 

 thick. No vascular bundles are found, and no stomates. We 

 have, therefore, scarcely more to examine then a single layer of 

 cells with their contents, so that the experiment can be performed 

 with the utmost readiness and certainty. 



If now one of these cells is examined, it will be found to 

 consist of a delicate, membranous cell-wall, containing a trans- 

 parent, fluid-like substance, in which float from twelve to twenty 

 round, green bodies. These latter are the so-called chlorophyll 

 bodies. 



