CALLOSE IN ROOT-HAIRS 



119 



1. Insoluble in water, alcohol and cuprammonia. 



2. Cold 1 % caustic potash caused rapid swelling and subsequent 

 solution of the callose within unbroken root-hairs. When a callosed 

 root-hair was stained with corallin, that the character of the thickening 

 might be more easily determined, and then cut across with a scalpel 

 and irrigated with 1% caustic potash solution, a very rapid swelling 

 could be watched. This swelling of the callose continued until a gelat- 

 inous mass exuded from the incision (fig. 11). Irrigation with water 

 followed by a solution of corallin showed that the gelatinous mass 

 was the swollen callose. The thin outer edges of the mass indicated 

 that the callose substance at that place was passing beyond the stage of 

 swelling into complete solution, such solution ceasing when the caustic 

 potash was displaced by water. In large root-hairs containing a small 

 plug of callose the caustic potash caused sufficient swelling of the plug 

 to give a uniform pale pink reaction with corallin throughout the entire 

 lumen of the hair when the stain was applied after irrigation with water. 



3. Cold 1 % caustic soda acted in the same manner as did the potash 

 solution, though less rapidly. 



4. Readily soluble in cold concentrated sulphuric acid. 



5. Readily soluble in a mixture of equal parts of concentrated solu- 

 tions of calcium and stannic chlorides. 



6. Swelled in cold solutions of alkaline carbonates and ammonia. 



7. Chlorozinciodide gave a red-brown color. At first a bluish tint 

 could be detected together with the brown. This disappeared on irri- 

 gation with water, leaving the cellulose part of the wall colorless and the 

 thickening substance a bright red-browm color which faded out after 

 an hour or more in water. 



8. Aniline blue in dilute aqueous solution gave a bright blue color 

 almost immediately. Preparations stained in this way held the color 

 for several weeks when mounted in glycerine. 



9. Corallin in 4 % carbonate of soda solution gave a color varying 

 with the concentration of the stain from bright pink to red. This stain 

 was not held permanently by the callose in any of the mounting media 

 tried. 



10. Aqueous aniline blue followed by calcium chloride and iodine 

 gave a rose-red color. 



11. Positive callose reactions in the thickenings of root-hairs have 

 also been found with reagents devised and employed for the detection 

 of callose in seive tubes by Dr. A. F. Hemenway, and hy him privately 

 communicated to me. Doubtless these reagents will be published by 

 him in the near future. 



All reagents and reactions stated above were tested on the 

 callose in the sieve tubes of Wistaria chinensis. 



The callose-thickened root-hairs are not confined to any one 

 species. They were found on young plants of three species of 

 Panicum grown in ordinary soil, on young plants of Zea mays L. 



