222 Pennington — A Chemico-Physiological 



diffused over the whole cell. Before this stage is reached, 

 the droplets at the edges of the bands of conjugating 

 material show more of a yellow tint than the corresponding 

 droplets in the vegetating bands. This difference in color 

 is plainly marked and indicates that we have here, in all 

 probability, a compound which leans toward etiolin rather 

 than toward normal chlorophyll. So marked is the differ- 

 ence, that the masses of conjugating threads have a 

 distinctly paler color than the others. 



Not only is the green substance in an unstable condi- 

 tion ; the framework of the band seems to have under- 

 gone a change also. This framework in the conjugating 

 cells is entirely effaced by continued treatment with 

 carbon disulphide or chloroform, while in the vegeta- 

 ting cells the outline of the band can be plainly seen, even 

 after the chlorophyll has been completely dissolved out. 

 Just what the fundamental difference is has not been 

 ascertained. It is probably closely correlated with another 

 observation which was made at this time. A microscopic 

 examination of those cells which had distinctly developed 

 tubes, showed clear refractive bodies lying on, or closely 

 against, the chlorophyll bands. The diameter of such a 

 droplet was sometimes as great as that of the band, 

 decreasing until it was represented by only a refractive 

 point. The substance was insoluble in cold and hot water, 

 but soluble in the usual solvents for fats. Osmic acid 

 colored it deep brown or black. This test must of 

 course be made after removing the tannin. It was accom- 

 plished by immersing the threads for a moment in boiling 

 water, then exposing them for a short time to the vapor of 

 osmic acid. 



Because of the resin found in the vegetating material, 

 and which was supposed to be contained in the chloro- 

 phyllaceous substance, these droplets were tested for such 

 compounds, following the idea that owing to the high state 

 of activity of the cell, and the marked changes which had 

 taken place, it was possible that the resin had been excreted 



