PROTOPLASMIC MOVEMENT. 409 



hairs of Hydrocharis), is showing the normal movement, a 

 temporary cessation only, takes place.^ 



Fresh -water Amoebae which I accustomed to salt water of 2*5 

 per cent, drew themselves rapidly together on the addition of 

 •J per cent, salt solution, but recommenced, however, to move 

 in the original manner after a few minutes. Czerny ~ has 

 made similar observations. 



Similar observations have also been made concerning the 

 influence of acids and alkalies. 



In Dutrochet's^ experiments on Chara an immersion for five 

 minutes in potash or soda of 0'05 per cent., or tartaric acid of 

 0*1 per cent., caused an acceleration of the movement. 



Kiihne* found that after very short and weak applications of 

 ammonia vapour to Actinosphserium the processes became 

 very small, short, and strougly varicose, but after a long pause 

 resumed their original condition. 



VI. Theoretical Conclusions. 



No theory of protoplasmic movements, leading back to their 

 elementary physical and chemical processes, can be deduced 

 from the hitherto collected facts. As it is, in fact, possible 

 only to directly perceive the mechanical portion of the process, 

 any theoretical conclusion must be limited to what relates to 

 the mechanism of the movements, and an investigation into 

 the nature and connection which the visible phenomena have 

 with the invisible molecular action which underlies them must 

 be left to futurity. 



Every attempt at an explanation of the mechanism of proto- 

 plasmic movements must not only take into account all the 

 known modifications of such movements, as Hofmeister^ has 



' Hofmeister, loc. cit., p. 53. 



^ V. Czerny, " Einige Beobacthungen iiber Amoben," ' Arcb. f. Mikr. 

 Anat.,' V, p. 158, 1869. 

 3 Dutrochet, ' Compt. rend.,' ii, p. 78, 1837. 



* Kiihue, 1. c, pp. 64- and 65 ; pp. 48 and 49 (Amoeba); p. 82 (Myxo- 

 mycetes); also Scbultze, 1. c., p. 32 (Actinosphaerium) ; and p. 37 

 (Miliola). 



* Hofmeister, ' Die Lehre von der Pflanzenzelle,' p. 59. 



