ON PROTRUSION OF PliOTOTLASMIC FILAMENTS. 2G7 



should be considered, nauiely, that the filaments may consist of 

 a liquid core of resinous matter, surrounded by a tubular shell 

 of protoplasm. Professor Eay Laiikester, who was kind enough 

 to examine preparations of living glands, suggested this idea. 

 He remarked that the monilifonn contraction gave him more the 

 impression of a tube closing on its contents tha)i of any possible 

 contraction of a solid body. I think this view ought to be con- 

 sidered, though I am not at present inclined to accept it. 



To return to the second of the above objections — viz. that the 

 protrusion of protoplasm is an incredibly wasteful method of 

 secreting. Two answers may be made to this objection. It 

 must be granted that if a wasteful, it is also a rapid way of 

 secreting, and it is impossible to know of how great importance 

 it may be that what is probably an excretion should be rapidly 

 eliminated. In the second place, it is quite possible or probable 

 that the filaments have not adhered to their original function of 

 removing waste products, but have assumed other functions. It 

 is perfectly conceivable that a protruded mass, consisting in part 

 of true, living, protoplasm, should, on finding itself surrounded 

 by a nitrogenous fluid, absorb and transmit nutriment to the 

 leaf. We know from my father's observations on Utricularia 

 that the trichomes lining the bladders are markedly afi'ected by 

 the absorption of nitrogenous fluids. And we have the same 

 kind of evidence in the case of the teasel. My father found 

 that a weak solution of the poison of the cobra-snake had a 

 j)owerfully stimulating effect on the tentacles of Drosera. A 

 solution of about 5 % produced more active aggregation 

 than can be produced by any other means, except, perhaps, 

 a moderately high temperature. The same solution of cobra 

 poison was tried with the teasel ; it not only produced a state of 

 activity in the filaments as already described, but was certainly 

 absorbed by the trichomes. At 4 p.m., when the solution was 

 applied, the contents of the trichomes were merely granular, 

 next morning the cells contained definite masses, which slowly 

 changed their forms. (See fig. TO.) This appearance must be 

 considered as " aggregation" ; and when it is remembered that 

 aggregation only occurs in the glands of Drosera, Pinguicula, Utri- 

 cularia, &c., when excited, it must be allowed that we have 

 evidence of the excitement of the glands of the teasel by the 

 absorption of the cobra solution. But too much stress must 

 not be laid on this phenomenon, as on some occasions it entirely 

 fails with cobra solution, and is a very rare occurrence under any 

 circumstances, and fig. 10 was drawn from a specimen simply 

 mounted in wafer for two or three days. Moreover, it seems 

 to have nothing to do with the filaments, for I have seen it on 

 two occasions in the glands of the fig, 1 type. I may here 



