42 HABITS OF WOKMS. Chap. I. 



grains are preserved in the guard-cells of the 

 stomata. Now in several cases the starch had 

 partially or wholly disappeared from these 

 cells, in the parts which had been moistened by 

 the secretion; while they were still well pre- 

 served in the other parts of the same leaves. 

 Sometimes the starch was dissolved out of 

 only one of the two guard-cells. The 

 nucleus in one case had disappeared, together 

 with the starch-granules. The mere burying 

 of lime-leaves in damp earth for nine days 

 did not cause the destruction of the starch- 

 granules. On the other hand, the immersion 

 of fresh lime and cherry leaves for eighteen 

 hours in artificial pancreatic fluid, led to the 

 dissolution of the starch-granules in the guard- 

 cells as well as in the other cells. 



From the secretion with which the leaves 

 are moistened being alkaline, and from its 

 acting both on the starch-granules and on 

 the protoplasmic contents of the cells, we 

 may infer that it resembles in nature not 

 saliva,* but pancreatic secretion ; and we 

 know from Fredericq that a secretion of this 



* C/laparede doubts wlietlier saliva is secreted by worms : see 

 * Zeitsclirift fiir wibsenschaft. Zoologie,' B. xix. 1869, p. 601. 



