Chap. III. THE PROCESS OF AGGREGATION. 43 



now all their cells had undergone aggregation ; so had the cells 

 of the exterior tentacles which had become inflected through 

 the irritation transmitted from the glands of the disc, on which 

 the transported particles rested. Tliis was likewise the case with 

 the short tentacles round the margins of the disc, which had not 

 as yet become inflected. This latter fact shows that the pro- 

 cess of aggregation is independent of the inflection of the ten- 

 tacles, of which indeed we have other and abundant evidence. 

 Again, the exterior tentacles on three leaves were carefully 

 examined, and found to contain only homogeneous purple fluid ; 

 little bits of thread were then placed on the glands of three of 

 them, and after 22 hrs. the purple fluid in their cells almost 

 down to their bases was aggregated into innumerable, spherical, 

 elongated, or filamentous masses of protoplasm. The bits of 

 thread had been carried some time previously to the central 

 disc, and this had caused all the other tentacles to become 

 somewhat inflected; and their cells had likewise undergone 

 aggregation, which however, it should be observed, had not 

 as yet extended down to their bases, but was confined to the 

 cells close beneath the glands. 



Not only do repeated touches on the glands* and the contact 

 of minute particles cause aggregation, but if glands, without 

 being themselves injured, are cut off from the summits of the 

 pedicels, this induces a moderate amount of aggregation in the 

 headless tentacles, after they have become inflected. On the 

 other hand, if glands are suddenly crushed between pincers, as 

 was tried in six cases, the tentacles seem paralysed by so great 

 a shock, for they neither become inflected nor exhibit any signs 

 of aggregation. 



Carbonate of Ammonia. — Of all the causes inducing aggrega- 

 tion, that which, as far as I have seen, acts the quickest, and is 

 the most powerful, is a solution of carbonate of ammonia. AVhat- 

 ever its strength may be, the glands are always affected first, 

 and soon become quite opaque, so as to appear black. For 

 instance, I placed a leaf in a few drops of a strong solution, 

 namely, of one part to 146 of water (or 3 grs. to 1 oz.), and 

 observed it under a high power. AH the glands began to 



* Judging from an account of the stamens of Berberis, after 



INI. Heckel's observations, which they have been excited by a 



I have only just seen quoted in touch and liave moved; for he 



the ' Gardener's Chronicle ' (Oct. says, " the contents of each indi- 



10, 1874), he appears to have vidual cell are collected together 



observed a similar phenomenon in in the centre of the cavity." 



