PECULIAR EFFECTS OF BARIUM, STRONTIUM, AND 



CERIUM ON SPIROGYRA 



S. S. Chien 



(with two figures) 



It has been pointed out by Osterhout 1 that dilute solutions of 

 BaCl 2 (o.ooi-o.oooi M) have a specific effect on certain species 

 of Spirogyra. They produce a peculiar contraction of the chloro- 

 plasts in the middle of the cell which is very characteristic. This 

 effect was not produced at this dilution by any of the other salts 

 examined. As specific effects of this kind are uncommon, it seemed 

 desirable to investigate the matter further. 



Two species of Spirogyra were investigated, a large form of the 

 S. crassa type, which was used by Osterhout, and a smaller species. 

 The method of contraction differs somewhat in the two species. 

 In both kinds contraction usually begins in the region near the ends 

 of the cell, but in the larger kind the chloroplasts sometimes begin 

 to contract in the central region. In a large percentage of the cells 

 of the larger kind the central region shows the greatest contraction. 

 The chloroplasts in this region may either shrink away from one 

 side of the cell wall more than from the other, or equally from all 

 sides. In the latter case the final shape (fig. i , B) assumed by these 

 bodies is quite typical for this kind of Spirogyra. In the smaller 

 kind the greatest shrinking occurs in regions between the center and 

 the ends of the cell (fig. 2, B). These are cells of the larger kind, 

 however, whose chloroplasts contract like those of the smaller kind, 

 and vice versa. In general the longer cells of each species are apt 

 to contract most toward the ends, while the shorter cells are apt 

 to have the greatest contraction in the middle. In either case the 

 contractions of the chloroplasts are very characteristic. 



Contraction usually takes place a few minutes after the applica- 

 tion of the solutions. Table I shows the time necessary for pro- 

 ducing the effect at different solutions. 



1 Osterhout, \Y. J. V., Specific action of barium. Amer. Jour. Botany 3:481- 



482. igi6. 



Botanical Gazette, vol. 63] 



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