3Q 



THE PHYSIOLOGY OF STOMATA. 



A similar result, excepting the sudden closure, may be obtained with the 

 stomata of Fouquieria splendens, and in an even more marked degree than 



in those of Verbena. They not only open 

 widely, but the guard-cells frequently sep- 

 arate from each other at one or both ends, 

 enlarge greatly, and become tilted with 

 reference to the epidermis. This enlarge- 

 ment and the distortion which accompanies 

 it appears to be due, not to the swelling of 

 the starch-grains, but of the thickened cell- 

 walls, as these changes are often quite as 

 great, even if the starch is in small amount 

 or is absent from the stoma. 



The behavior of the stomata of Galtonia 

 lO) — was induced by Leitgeb by killing with 



iodine vapor and chloroform, and the opening 

 under these reagents was quite as marked as 

 in my fig. 9, which shows the forms assumed 

 by stomata on treatment with strong potas- 

 sium hydrate. It would seem, however, that 

 the immediate cause of the opening is not 

 the same as in the case here recorded. 



<3© 



Fig. 9. — Forms assumed by stomata on 

 treatment with strong potassium 

 hydrate. Uppermost left-hand figure 

 from Verbena; others Fouquieria. Low- 

 est right-hand figure shows that the 

 guard-cells become tilted with respect 

 to epidermis. 



