1896.] NATURAL SCIENCES OF PHILADELPHIA. 215 



jihores (c7i) within these are very conspicuous. They are rather 

 closely packed together and lie parallel to each other. In color they 

 are bright red, and in form very narrowly spindle-shaped. Below the 

 epidermis, the cells constituting the rest of the pulp of the aril are 

 of larger dimensions, and the chromatophores seem scattered iri-egu- 

 larly through the cells. The drawing shows also the groove (g) be- 

 tween the arils of two adjoining seeds. Attention has been called to 

 the fact that the study of chromatophores and pigments can be carried 

 on with entire certainty only within the living cells on account of 

 their ready decomposition. When I collected my material I had not 

 the opportunity of careful examination, but the resistance which 

 this tissue manifests to powerful reagents, leads me to conclude 

 that in all probability the arrangement as above described is iden- 

 tical with that of the living material. I found further that sections 

 from the dried seeds did not show any difference in appearance 

 from that represented in the drawing. 



According to Zimmermann^ the pigments of chromatophores found 

 in phanerogams, regarding which we have somewhat definite de- 

 scriptions, are as follows : 



1. Chlorophyll green. 



2. Carotin including chlorophyll yellow. 



3. Xanthin. 



4. Coloring matter of Aloe flowers. 



Although certain reactions are characteristic of each of these four 

 pigments, and although an abundant literature exists, at least so far 

 as the first of these, chlorophyll green, is concerned, we can not with 

 any justification claim even such knowledge as the chemist has in 

 reference to many organic compounds of the various complex series. 

 A formula is attempted only for carotin which is said to be C^g Hjg. 

 The great difficulty in investigating these pigments lies in their un- 

 willingness to crystallize. Carotin is the only one of these four 

 which occurs within the vegetable cell in crystalline form, and 

 which can be again crystallized when extracted from the plant. In 

 regard to amorphous extractions complete certainty is always want- 

 ing as to the puiity of the product, i. e., whether we have a chemical 

 individual to deal with or with a mixture of more or less closely 

 related compounds. 



^ Zimmermann, Botanical Microtechnique. Translated by James Ellis Hum- 

 phrey, N. Y., 1893. 



