CRAP. XVI. SECRETION, ABSORPTION, DIGESTION. 385 



which was left being of a dirty colour, including globules of oil. 

 They thus differed in appearance from other grains kept in 

 water for the same length of time. The glands in contact with 

 the pollen-grains had evidently absorbed matter from them ; for 

 they had lost their natural pale-green tint, and contained aggre- 

 gated globular masses of protoplasm. 



(14) Square bits of the leaves of spinach, cabbage, and a 

 saxifrage, and the entire leaves of Erica tttralix, all excited the 

 glands to increased secretion. The spinach was the most effec- 

 tive, for it caused the secretion evidently to increase in 1 hr. 

 40 m., and ultimately to run some way down the leaf; but the 

 glands soon began to dry, viz. after 35 hrs. The leaves of Erica 

 tetralix began to act in 7 hrs. 30 m., but never caused much 

 secretion ; nor did the bits of leaf of the saxifrage, though in 

 this case the glands continued to secrete for seven days. Some 

 leaves of Pinguicula were sent me from North Wales, to which 

 leaves of Erica tetralix and of an unknown plant adhered ; and 

 the glands in contact with them had their contents plainly 

 aggregated, as if they had been in contact with insects ; whilst 

 the other glands on the same leaves contained only clear 

 homogeneous fluid. 



(15) Seeds. A considerable number of seeds or fruits se- 

 lected by hazard, some fresh and some a year old, some soaked 

 for a short time in water and some not soaked, were tried. The 

 ten following kinds, namely cabbage, radish, Anemone r/emo- 

 ro*a, Rumex acetosa, Carex syluatica, mustard, turnip, cress, 

 Ranunculus acris, and Avena pubescens, all excited much secre- 

 tion, whic'i was in several cases tested and found always acid. 

 The five first-named seeds excited the glands more than the 

 others. The secretion was seldom copious until about 24 hrs. 

 had elapsed, no doubt owing to the coats of the seeds not being 

 easily permeable. Nevertheless, cabbage seeds excited some 

 secretion in 4 hrs. 30 m. ; and this increased so much in 18 hrs. 

 as to run down the leaves. The seeds or properly the fruits of 

 Carex are much oftener found adhering to leaves in a state of 

 nature than those of any other genus ; and the fruits of Carex 

 sylvatica excited so much secretion that in 15 hrs. it ran into 

 the incurved edges ; but the glands ceased to secrete after 

 40 hrs. On the other hand, the glands on which the seeds 

 of the Rumex and Avena rested continued to secrete for nine 

 days. 



The nine following kinds of seeds excited only a slight 

 amount of secretion, namely celery, parsnip, caraway, Linum 

 yrandijloruin. Cassia, Trifolium pannonicum, Plantago, onion, 



