198 DROSERA ROTUNDIPOLIA. [Chap. X. 



protoplasm in a tentacle has been aggregated, its redissolu- 

 tion always begins in the lower part, and slowly travels up 

 the pedicel to the gland, so that the protoplasm last aggre- 

 gated is first redissolved. This probably depends merely on 

 the protoplasm being less and less aggregated, lower and 

 lower down in the tentacles, as can be seen plainly when 

 the excitement has been slight. As soon, therefore, as the 

 aggregating action altogether ceases, redissolution naturally 

 commences in the less strongly aggregated matter in the 

 lowest part of the tentacle, and is there first completed. 



Direction of the Inflected Tentacles. When a particle of 

 any kind is placed on the gland of one of the outer tentacles, 

 this invariably moves towards the centre of the leaf; and so 

 it is with all the tentacles of a leaf immersed in any exciting 

 fiuid. The glands of the exterior tentacles then form a ring 

 round the middle part of the disc, as shown in a previous 

 figure (Fig. 4, p. 9). The short tentacles within this ring 

 still retain their vertical position, as they likewise do when 

 a large object is placed on their glands, or when an insect is 

 caught by them. In this latter case we can see that the 

 inflection of the short central tentacles would be useless, as 

 their glands are already in contact with their prey. 



The result is very different when a single gland on one 

 side of the disc is excited, or a few in a group. These send 

 an impulse to the surrounding tentacles, which do not now 

 bond towards the centre of the leaf, but to the point of ex- 

 citement. We owe this capital observation to Nitschke,* 

 and since reading his paper a few years ago, I have re- 

 peatedly verified it. If a minute bit of meat be placed by 

 the aid of a needle on a single gland, or on three or four to- 

 gether, halfway between the centre and the circumference of 

 the disc, the directed movement of the surrounding tentacles 

 is well exhibited. An accurate drawing of a leaf with meat 

 in this position is here reproduced (Fig. 10), and we see the 

 tentacles, including some of the exterior ones, accurately di- 

 rected to the point where the meat lay. But a much better 

 plan is to place a particle of the phosphate of lime moistened 

 with saliva on a single gland on one side of the disc of a 

 large leaf, and another particle on a single gland on the op- 

 posite side. In four such trials the excitement was not suf- 



Dot. Zettung,' 1800, p. 240. 



