20 DROSERA ROTUNDIFOLIA. [Chap. II. 



one side of a leaf, as near as possible to its circumference, the 

 tentacles on this side are first affected, those on the opposite 

 side much later, or, as often occurred, not at all. This was 

 repeatedly proved by trials with bits of meat; but I will here 

 give only the case of a minute fly, naturally caught and still 

 alive, which I found adhering by its delicate feet to the 

 glands on the extreme left side of the central disc. The mar- 

 ginal tentacles on this side closed inwards and killed the 

 fly, and after a time the edge of the leaf on this side also be- 

 came inflected, and thus remained for several days, whilst 

 neither the tentacles nor the edge on the opposite side were in 

 the least affected. 



If young and active leaves are selected, inorganic particles 

 not larger than the head of a small pin, placed on the central 

 glands, sometimes cause the outer tentacles to bend inwards. 

 But this follows much more surely and quickly, if the object 

 contains nitrogenous matter which can be dissolved by the 

 secretion. On one occasion I observed the following unusual 

 circumstance. Small bits of raw meat (which acts more 

 energetically than any other substance), of paper, dried moss, 

 and of the quill of a pen were placed on several leaves, and 

 they were all embraced equally well in about 2 hrs. On other 

 occasions the above-named substances, or more commonly par- 

 ticles of glass, coal-cinder (taken from the fire), stone, gold- 

 leaf, dried grass, corlj^ blotting-paper, cotton-wool, and hair 

 rolled up into little balls, were used, and these substances, 

 though they were sometimes well embraced, often caused no 

 movement whatever in the outer tentacles, or an extremely 

 slight and slow movement. Yet these same leaves were 

 proved to be in an active condition, as they were excited to 

 move by substances yielding soluble nitrogenous matter, such 

 as bits of raw or roast meat, the yolk or white of boiled egg^, 

 fragments of insects of all orders, spiders, <S:c. I will give 

 only two instances. Minute flies were placed on the discs of 

 several leaves, and on others balls of paper, bits of moes and 

 quill of about the same size as the flies, and the latter were 

 well embraced in a few hours; whereas after 25 hrs. only a 

 very few tentacles were inflected over the other objects. The 

 bits of paper, moss, and quill were then remove<l from these 

 leaves, and bits of raw meat placed on them ; and now all the 

 tentacles were soon energetically inflected. 



