1896.] NATURAL SCIENCES OF PHILADELPHIA. 213 



synthetic preparation of alizarin, alcohol, indigo, oxalic, citric, tar- 

 taric and salicylic acids, vanillin and finally sugars, to call to mind 

 a host of further illustrations. On the other hand it must be admit- 

 ted that this victory, great as it is, has sometimes been overrated 

 and has tended to make the scientist overbearing as shown by his 

 attempts to resolve the phenomena of life into a simple operation of 

 chemical and physical forces, without taking duly into consideration 

 the highly organized structure of the protoplasmic mass, whose har- 

 monious operation with a set of external conditions is manifested by 

 what we call life. It is because of the exceedingly intricate mechan- 

 ism of the protoplasmic structure, of whose operations we know very 

 little, that our knowledge of the products of its activity is still 

 extremely incomplete. Only in such cases, when we can obtain pro- 

 ducts capable of crystallizing, can we with any certainty state that 

 we have to deal with chemical individuals whose formulas may be 

 ascertained. If amorphous we cannot be sure but that we have 

 instead of one, a mixture of substances more or less closely allied. 



Before going further in the discussion of these plant products a 

 few more words should be said in regard to the organs which bear 

 the colors. The protoplasmic corpuscles have been appropriately 

 designated chromatophores, which name is now generally accepted. 

 It has been observed that as a rule, yellow, orange and brown 

 (sometimes blue) coloring matters are deposited in such chromato- 

 phores, while white, violet, blue and red (sometimes yellow) are 

 usually caused by a solution of the pigment in the cell -sap. It has 

 been found desirable to make a distinction between the kinds of 

 chromatophores. They are for convenience classified as follows : 

 chloroplasts, chromoplasts and leucoplasts, the latter class, which 

 are the colorless color bearers, being one of the contradictions in 

 which the systems of human classification abound. The bond of 

 sympathy is, however, their common origin, the fact that one may 

 be converted into the other according to the conditions, and each 

 one can originate only as a result of the division of pre-existing 

 chromatophores. 



Chloroplasts, as their name indicates, are the green bodies which 

 impart the green color characteristic of leaves and stems. The 

 pigment in this case can be readily extracted by means of such 

 solvents as alcohol, ether and chloroform, while the matrix remains 

 behind as a definitely shaped, colorless mass of protoplasm. The 

 pigment itself may under the influence of various factors, external 

 or internal, undergo modifications into chemically different sub- 

 stances, such as etiolin. 



