102 THEORETICAL AND GENERAL 



fibrillae, which in streaming cells would necessarily be confined to the 

 non-moving layer of ectoplasm. 



SECTION 46. Nerve-flbrillae in Plants. 



Nemec l states that longitudinal strands of fibrillae can be seen in 

 the cells at the apices of roots, and that these are always connected with 

 the nuclei in young cells. These fibres seem to pass from cell to cell 

 along the longitudinal rows of cells in the plerome, but when present 

 in the periblem they are usually more radially arranged. They were 

 observed by Nemec only in dead cells fixed in acid media, or just before 

 the death of cells placed in neutral or alkaline methyl-blue. Klemm 2 

 has, however, shown that fibrillar structures can be produced by the action 

 of various chemical agents, and that this condition of the protoplasm is 

 only temporary, if it be not fatally affected. Similar temporary but 

 pronounced longitudinal striations were observed by the author 3 in 

 plant-cells as the result of treatment with ether. 



Nemec (1. c., pp. no seq.), however, states that- chloroform, ether, 

 plasmolysis, low and high temperatures cause the fibrillar bundles observed 

 by him to disappear 4 . He also finds that they become more strongly 

 marked as the result of stimulation. Apparently, therefore, although 

 not permanent structures, they may represent the channels along which 

 stimuli are more readily transmitted than through the general protoplasm. 

 If so, their increased development after stimulation would partly explain 

 the slow but ultimate response of far removed parts to stimuli, which 

 produce no effect upon them if of short duration. 



According to Nemec (1. c., p. 128), small but sudden changes of 

 temperature cause the fibrillae to disappear, and the power of propagating 

 stimuli is almost or entirely lost until they reappear again. This apparent 

 connexion with the reappearance of the fibrillae may, however, be merely 

 accidental, for the sudden change of temperature may have temporarily 

 inhibited the power of response, and not the power of propagation. In 

 any case, the rates of propagation given by Nemec are slower than in 

 certain cases observed by the author in which no fibrillar bundles were 

 perceptible. 



Comparison between a nerve-imiscle preparation and a streaming 

 cell. Hormann apparently supposes a close analogy to exist between 

 a nerve-muscle preparation and a Nitella cell, but a variety of facts 



1 Die Reizleitung, Jena, 1901, p. 71. 



* Jahrb. f. wiss. Hot., 1895, Bd. xxvm, p. 696. 



3 Ewart, Journ. Linn. Soc., 1895, Vol. XXXI, p. 411. 



* Similar effects were noted in the rudimentary nerve-nbrillae of animals by Monckenburg and 

 Bethe, Archiv f. mikr. Anat, 1899, Bd. LIV. 



