MacDougal: tubers of isopyrum biternatum. 509 



few of the intact cells, in the injured ones, and in the fluid 

 around were a number of radially arranged groups of slender 

 or needle shaped incomplete crystals. These crystals are 

 easily soluble in water, insoluble in alcohol and acetic acid, 

 and must have been mixtures of bitartrate of potassium and cal- 

 cium (IV, p. 56). In a farther differentiative test of crystal of 

 ammonium oxalate placed at the edge of a cover glass diffused 

 through the water in which the section was mounted forming 

 a great number of tetragonal pyramidal and monosymmetric 

 rhombohedral forms. Ammonium carbonate gave a similarly 

 marked reaction, and if a drop of sulphuric acid were added to 

 the ash a plentiful supply of gypsum needles were formed. 

 The calcium occurs also in occasional crystals of the oxalate in 

 the stems and rhizomes. Treatment of the ash of tubers with 

 platinum bichloride gave a large number of the characteristic 

 crystal forms of potassium-platinum-chloride. On the ad- 

 dition of a solution of sodium phosphate containing a trace of 

 ammonia to the ash of tubers a moderate amount of ammonium- 

 magnesium-phosphate crystals were formed. 



Calcium was found somewhat evenly distributed through the 

 parenchyma of the tubers and in a large proportion of the cortex 

 of the same. In the leaves the greatest amounts were found in 

 the conducting sheaths of the fibro- vascular tissue, and in the 

 epidermal cells of the entire organ in great plenty. The ap- 

 plication of the platinum bichloride test to leaf stalks shows 

 also a very large amount of potassium in the leaf lamina. 

 While no quantitative determinations could be made it was ap- 

 parent that the amount of this substance steadily increased 

 from the root- tubers to the leaves. The amount of magnesium 

 present in the leaf, stem, and tuber showed no great variation, 

 though doubtless an exact determination would reveal distinct 

 differences. 



With a view to the possible discovery of the conditions, which 

 determine the formation of "red starch" recourse was had to 

 the methods of Godlewski (II), Boehm (I), Schimper (XII), 

 Meyer (IX) and Rendle (XI). In these tests chlorophyll-bear- 

 ing areas of the plant were exposed to atmospheres contain- 

 ing proportions of carbon dioxide from the normal to 25 per 

 cent, and at the same time, or separately to solutions of cane 

 sugar varying in strength from 5 per cent, to saturation. The 

 tubers and other tracts containing colorless chromatophores 

 were placed in solutions of cane sugar glycerine, glucose, 

 glycogen, asparagin, etc. 



