506 MINNESOTA BOTANICAL STUDIES. 



newed and kept free from water, the globules remained intact. 

 Sections containing the globules were placed in a small amount 

 of alcohol (95 per cent.) for ten days and were unchanged. 

 After 100 days in absolute alcohol the globules had taken on a 

 firmer consistency, and an ovoid, or irregular form (See PI. 29 

 Fig. 4). In the ovoid and globoid forms an appearance of 

 stratification could be detected, but no exact determination 

 could be made. From time to time fusion of two or more of the 

 globules in freshly treated sections occurred, and this fusion 

 was greatly facilitated by warming to 50° C. Although Kraus 

 obtained globules in the sugar laden cells on the addition of 

 glycerine, the test was scarcely successful in Isopyrum. Only 

 a few lumpy aggregations against the walls of the parenchy- 

 matous cells might be seen. Further if strong alcohol were 

 added to the preparation the globules were formed in great 

 numbers outside of the cells showing the dialyzation of the 

 sugar by the glycerine. Ether and chloroform caused no re- 

 action in the cells, although in sections remaining in these 

 fluids the globules previously formed were fused by their 

 mechanical action in the extraction of the alcohol. Solutions 

 of iodine gave no decided reaction either on the cell sap or 

 on the globules. In order to determine the presence or 

 absence of a membrane of precipitation on the globules 

 formed by alcohol, Congo red and a number of aniline stains 

 were applied but no such formation could be found. An 

 extract obtained by macerating 100 grams of fresh tubers taken 

 from the soil in April, showed an active sugar which turned 

 the plane of polarization to the right. On the addition of a 

 mineral acid the sugar became inactive. This and the marked 

 reaction obtained in the red color resulting from the use of 

 thymol and sulphuric acid both on fresh sections and the ex- 

 tract indicated a large proportion of sugar present. Sections 

 of tuber placed iu solution of methylene blue in absolute 

 alcohol gave the usual aggregation which, however, contained 

 none of the coloring matter. When placed in a weak solution 

 of caffein in water a small amount of plasmolysis was observ- 

 able in the meristematic cells but no aggregation of any sort 

 in the reserve laden parenchyma. On the addition of strong 

 alcohol to the sections thus treated the globules were formed 

 in the usual manner. 



The tubers gave a strong acid reaction which was found to 

 be due to the presence of a complex organic acid for which no 

 test was available. This acid seemed to be uniformly present 



