THE DETAILED ACTION OF POISONS 267 



It remains therefore to be determined whether the protoplasm of Penidllium 

 is as sensitive to salts of copper as that of other plants. It is worthy of note 

 that various poisonous heavy metals are not absorbed by the intact lining epithelium 

 of the alimentary canal \ 



SECTION 74. The Detailed Action of Poisons {continued). 



The different parts of the protoplast have not all the same power of 

 resistance to poisons. Thus in the case of Penidllium the plasmatic 

 membrane is presumably more resistant than the rest of the protoplasm, 

 and it often happens that a poison kills the nucleus before the cytoplasm 

 is fatally affected 2 . Probably also poisonous aniline dyes will exert most 

 influence upon those organs which absorb and accumulate them to the 

 greatest extent 3 . This may be in some cases the nucleus, in others the 

 cytoplasm, but owing to the general similarity of composition it is 

 only natural that all poisons which kill the nucleus should ultimately kill 

 the cytoplasm as well. Similarly the fact that chloroform and ether 

 produce a cessation of protoplasmic streaming both in the presence and 

 absence of the nucleus, shows that they act directly upon the cytoplasm 

 and not upon the nucleus alone 4 . 



Without doubt the power of resistance varies in the different cells and 

 organs of a plant. When, however, a single organ such as a leaf is killed 

 by poison, the plant as a whole will not be more affected than by the 

 direct removal of the leaf, whereas in the case of a vertebrate animal any 

 poison which acts injuriously upon the heart, lungs, or nervous mechanism 

 will ultimately produce death. 



It is easy to understand that acids and alkalies should act as poisons 

 in virtue of their pronounced chemical activity, and that the same should 

 be the case with all substances which combine with the proteid or other 

 constituents of protoplasm. It is also possible that loose chemical union, 

 or physical absorption, or catalytic action may produce death. Indeed 

 the poisonous action of aniline dyes, chloroform, ether, and alkaloids 

 seems to be due to their loose chemical union with the protoplasm. 



are soluble in fats, although neither the nitrate, sulphate, nor alkaline solutions of copper can 

 penetrate Penidllium. 



1 Kunkel, Toxicologie, 1899, p. 119. 



2 Pfeffer, Unters. a. d. Bot. Inst. zu Tiibingen, 1886, Bd. II, pp. 206, 276 ; Klemm, Jahrb. f. wiss. 

 Bot., 1895, Bd. xxvui, p. 687. 



3 Pfeffer, I.e., p. 273; D. H. Campbell, ibid., 1888, Bd. II, p. 569. 



4 By appropriate treatment the ectoplasm can be killed before the streaming endoplasm is 

 fatally affected, and the chloroplastids can be killed without the rest of the cell being seriously 

 injured. The order of death in the different parts of the cell varies according to the agency used 

 and its mode of application. Cf. Ewart, Journ. of Linn. Soc., 1896, Vol. xxxi, pp. 406, 574; On 

 the Physics and Physiology of Protoplasmic Streaming, Clar. Press, 1903, p. 98. 



