813 PINGUICULA VULGARIS. [Chap. XVL 



our, including globules of oil. They thus tlifTered 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 aggregated globular masses of protoplasm. 



(14) Square bils of the leaves of spinach, cabbage, and a saxi- 

 frage, and the entire leaves of Erica tetralix, all excited the glands 

 to increased secretioq. The spinach was the most effective, for it 

 caused the secretion evidently to increase in 1 hr. 40 m., and ul- 

 timately to run some way down the leaf; but the glands soon be- 

 gan 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 selected 

 by hazard, some fresh and some a year old, some soaketl for a 

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

 following kinds, namely, cabbage, radish, Anemone nemorosa, Ru- 

 mcx acetosa, Carex sylvatica, mustard, turnip, cress, RanunculM 

 acris, and Arena pubcscens, all excited much secretion, which waa 

 in several cases tested and always found acid. The five first- 

 named seeds excited the glands more than the others. The secre- 

 tion was seldom copious until about 24 hrs. had elapsed, no doubt 

 owing to the coats of the seeds not being easily permeable. Never- 

 theless, 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 secre- 

 tion that in 15 hrs. it ran into the incurved edges; but the glands 

 ceasecl to secrete after 40 hrs. On the other hand, the glands on 

 which the seeds of the Ilumex and Avcna rested continued to se- 

 crete for nine days. 



The nine following kinds of seeds excited only a slight amount 

 of secretion, namely, celery, parsnip, caraway, Linum grandi- 

 flortim, Cassia, Trifoliiim pannonicvm, Plantago, onion, and Hro- 

 mus. Most of these seeds did not excite any secretion until 48 hrs. 

 had elapsed, and in the case of the Trifolium only one seed acted, 

 and this not until the third day. Although the seeds of the 

 PlanUigo excite<l very little secretion, the glands continued to se- 

 crete for six tiays. Lastly, the five following kinds excite<l no 

 secretion, though left on the leaves for two or three days, namely, 

 lettuce. Erica tetralix, Atriplrx hortensia, Phalarls cnnariensis, 

 and wheat. Nevertheless, when the soels of the lettuce, wheat, 

 and Atriplex were split open and applied to leaves, secretion wa 

 excited in considerable (quantity in 10 hrs., and I believe that 



