RESEARCH SEMINAR. 255 







carp up to the period of spore formation, and approximately 

 eight in those of the thallus, the reduction division being imme- 

 diately associated with the production of carpospores. 



July 27. The Origin and Nature of Color in Plants. By DR. 



HENRY KRAEMER. 



Color in plants is due to definite constituents which either 

 themselves are colored or they produce colors when acted upon 

 by other substances. These constituents are either associated 

 with some of the organized bodies of the plant cells, or they 

 occur in the cell-sap. To the former belong the pigments asso- 

 ciated with the etioplasts, chloroplasts and chromoplasts. These 

 are distinguished from all other color substances of the plant by 

 their solubility in ether, benzol, xylol, chloroform and similar 

 solvents. 



Besides the plasted pigments there are substances dissolved in 

 the cell -sap. These occur in all parts of the plant and give rise 

 to the other shades and tints than yellow and green. They are 

 quite soluble, usually in a 50 per cent, hydro-alcoholic solu- 

 tion, and are insoluble in the above-mentioned solvents. They 

 give well-marked reactions with certain groups of reagents and 

 show many properties in common whether obtained from flowers, 

 leaves, fruits, roots or stems. 



The relationship of the chloroplastid to the production of 

 starch has already been pointed out. The occurrence of proteid 

 substances in chromoplastids suggests that they have the special 

 function in the manufacturing or storing of nitrogenous food 

 material which is subsequently utilized in the development of the 

 ovule, germinating plant or biennial plant. The wide distribu- 

 tion of cell-sap colors, which share many general properties in 

 common, suggests that these substances, like other unorganized 

 cell contents, are but incidental to physiological activity. 



August i. Sexual Reproduction of the Mucorineae. By A. 



F. BLAKESLEE. 



According to their methods of zygospore formation the Muco- 

 rinese may be divided into two groups. In the homothallic group 

 zygospores are developed from branches of the same thallus. In 

 the heterothallic group zygospores are developed from branches 



