50 Proceedings of Indiana Academy of Science 



sugar, the starch was completely removed from grains of maize or 

 other plants (73). 



In the field of microchemistry much of interest to the plant physi- 

 ologist remains to be done. This work has been ably carried out, especially 

 by Tunmann (74) and Molisch (75). The application of chemistry 

 should go hand in hand with plant physiology. As we glance through the 

 latter subject we see, as a rule, far too little of the use and knowl- 

 edge of chemistry. The masterful work of Czapek (41) and others 

 have rendered service of great value along this line. With this brief 

 idea of physiology's great helper we turn our attention in conclusion 

 to some special problems where it is concerned. 



A change took place in chemistry when Wohler in 1828 obtained 

 urea from ammonium cyanate and thus produced for the first time an 

 organic from an inorganic compound. Then Kolbe synthesized tri- 

 chloracetic acid in 184.5 and Berthelot synthesized alcohol from formic 

 acid thus removing the boundary between organic and inorganic chem- 

 istry (76). Organic chemistry, the chemistry of carbon compounds, 

 has tried to do what plants do, and in many cases has apparently suc- 

 ceeded. The plant no longer furnishes alizarin and indigotin for com- 

 merce which are now obtained from coal tar and even some alkaloids 

 have been prepared artificially. 



Since colloids were first investigated by Graham the similar natui-e 

 of protoplasm has given their study a significance. Later the principle 

 of Tyndall's phenomenon was applied by Zsigmondy to the so-called 

 ultramicroscope so that protoplasm and living cells can be studied to 

 advantage. Recently Czapek (77) has investigated the question of 

 surface tension in plant cells and has called attention to the applica- 

 tion of Richardson's Law. We have to do here especially with the 

 behavior of two important substances in the plant cell, protoplasm and 

 chlorophyll. Their activities go hand in hand in green plants. We 

 shall now turn our attention to the behavior of the chlorophyll in par- 

 ticular. Glancing backward we recall that the green coloring substance 

 of plants was recognized by Nehemiah Grew (78) in 1682 and that it 

 was given the name of chlorophyll in 1817 by Pelletier and Caventon 

 (41, Bd. I, p. 556). Numerous and valuable contributions have been 

 produced in rapid succession and yet almost 250 years after Grew's 

 work the performances of this riddle are unsolved. Colored lights have 

 an effect on certain plants, for it is claimed that in red light specimens 

 of Oscillatoria become green, in green light they turn led and in blue 

 light assume a yellow hue (79, p. 245). Problems in great number 

 remain to be answered as questions concerning a chloroplast membrane 

 and the influence of chloroplasts on various cytoplasmic movements 

 (79, p. 251). The positions assumed by chloropla.-ts so ably investigated 

 by Stahl and Senn (80) still leave many points to be solved. The ques- 

 tion of structure in certain respects is still doubtful as is the exact form 

 of the chlorophyll in the chloroplast and points concerning yellow pig- 

 ments (1, Bd. i, p. 297). 



The greatest advances on the subject of chlorophyll so far are the 

 investigations of Willstatter and Stoll (81). Their published papers deal 



