314 PINGUICULA VULGARIS. [Chap. XVL 



plants growing in a state of nature; and of these, though kept 

 for five iiiuntha on damp sand, none germinated, some being then 

 evidently dead. 



The Effects of Objects not containing Soluble Nitrogenous Matter. 



(10) It has already been shown that bits of glass, placed on 

 leavel, excite little or no secretion. The small amount which 

 lay beneath the fragments was tested and found not acid. A bit 

 of wood excited no secretion; nor did the several kinds of seeds of 

 which tixe coats are not permeable to the secretion, and which, 

 therefore, acted like inorganic bodies. Cubes of fat, left for two 

 days on a leaf, produced no effect. 



(17) A particle of white sugar, placed on a leaf, formed in 1 

 hr. 10 m. a large drop of fluid, which in the course of 2 additional 

 hours ran down into the naturally inflected margin. This fluid 

 was not in the least acid, and began to dry up, or more probably 

 was absorbed, in 5 hrs. 30 m. The exijerinient was repeated; par- 

 ticles being placed on a leaf, and others of the same size on a 

 slip of glass in a moistened state; both being coverel by a bell- 

 glass. This was done to see whether the increased amount of 

 fluid on the leaves could be due to mere deliciuescence; but this 

 was proved not to be the case. The particle on the leaf caused so 

 much secretion that in the course of 4 hrs. it ran down across two- 

 thirds of the leaf. After 8 hrs. the leaf, which was concave, was 

 actually filled with very viscid fluid; and it particularly deserves 

 notice that this, as on the former occasion, was not in the least 

 acid. This great amount of secretion may be attributed to exos- 

 mose. The glands which had been covered for 24 hrs. by this fluid 

 did not differ, when examined under the microscope, from others 

 on the same leaf, which had not come into contact with it. This 

 is an interesting fact in contrast with the invariably aggregated 

 condition of glands which have l)een bathed by the secretion, when 

 holding animal matter in solution. 



(18) Two particles of gum arable were placed on a leaf, and 

 they certainly caused in 1 hr. 20 m. a slight increase of secretion. 

 This continued to increase for the next 6 hrs., that is for as long 

 a time as the leaf was observed. 



(19) Six small particles of dry starch of commerce were placed 

 on a leaf, and one of these caused some secretion in 1 hr. 15 m., 

 and the others in from 8 hrs. to 9 hrs. The glands which had thus 

 been excited to secrete soon became dry, and did not l)egin to se- 

 crete again until the sixth day. A larger bit of starch was then 

 placed on a leaf, and no secretion was excited in 5 hrs. 30 m. ; but 

 after 8 hrs. there was a considerable supply, which increased so 

 much in 24 hrs. as to run down the leaf to the distance of J of 

 an inch. This secretion, though so abundant, was not in the 

 least acid. As it was so copiously excited, and as seeds not mrely 

 adhere to the leaves of naturally growing plants, it occurred to 

 me that the glands might j)erhap have the |)ower of secreting a 

 ferment, like ptyaline, capable of dissolving starch; so I carefully 



