30 



Hydration and Growth. 



lages and gums elude microchemical tests. It has already been pointed 

 out that it is in this condition that they produce the peculiar hydration 

 properties of living matter which are those of an agar-protein gel.^ 



Generally the mucilages originate in minute quantities in numerous 

 places in the protoplasm, but when such structures as starch-grains or 

 layers of wall material are transformed, the gels so formed largely re- 

 mains in place, and as they swell to occupy a much larger space than 



Table 11. — Hydration of sections containing gums and mucilages. 



Agar (17° C.) 



Agar 6, prosopia gum 2, gel. 1, bean 



protein 1 (25° C.) 



Agar 6, gum arabio 3, gel. 1 (14r- 



17° C.) 



Agar 8, cherry gum 2 (16° C.) 



Agar 6, cherry gum 3, gel. 1 (16° C). 

 Agar 8, cherry gimi (precip.), 2. . . . 



Agar 8, gel. 2 (16° C.) 



Agar 8, tragacanth 2 (15° C.) 



Tragacanth (15° C.) 



Opuntia mucUage (15° C.) 



Distilled 

 water. 



Citric 



acid, 



0.01 N. 



p. ct. 

 1,300 



1,182 



957 



572 



889 



912 



1,050 



1,100 



947 



1,367 



1,500 



1,500 



650 



Sodium 

 hydrojdd, 

 0.01 M. 



p. ct. 

 602 



824 

 478 

 458 

 639 

 556 

 750 

 520 

 474 

 778 

 731 

 731 

 350 



Potassium 

 nitrate, 

 0.01 M. 



p. ct. 

 1,700 



1,250 

 1,389 

 1,082 

 1,100 

 1,268 

 1,347 

 1,725 

 1,346 

 1,200 

 300 



Agar 6, opuntia mucilage 2, bean protein 1, 



gel. 1 (26-27° C.) 



(22° C.) 



Gelatine 90, cactus mucilage 10 



Average 



Gelatine 100, agar 5, averages 



Gelatine 80, agar 20, averages 



Water. 



p. ct. 

 1,780 

 2,400 



500 

 425 

 400 

 387 



428 



329 

 431 



Hydrochloric 



acid, 



O.OIM. 



p. ct. 

 780 



900 

 806 

 762 

 806 

 706 



770 



850 

 789 



Sodium 



hydroxid, 



O.OIM. 



p. ct. 

 1,060 



950 

 562 

 531 

 575 

 612 



657 



685 

 431 



that occupied by the bodies from which they were formed, the resultant 

 masses may be so large as to crowd the protoplasm into a small com- 

 pass.^ Their hydration offers such indeterminate features as to make 



' Spoehr, H. A. Carbohydrate economy of the cacti. Carnegie Inst. Wash. Pub. No. 287 



pp. 44-47. 1919. 

 ^Stewart, E. G. Mucilage or slime formation in the cacti. Bull. Torr. Bot. Club 46:175. 



1919. Lloyd, F. E. The origin and nature of the mucilage in the cacti and in certain 



other plants. Amer. Jour, of Bot., 6:156. 1919. 



