1877.] 



Protoplasmic Filaments from the Teasel, 



5 



The substance of which the filaments are composed is gelatinous, 

 transparent, highly refracting, and devoid of granules. It is in a great 

 measure soluble in alcohol, is stained by tincture of alkanet, and not 

 blackened by osmic acid, and is coloured yellow by iodine. These reac- 

 tions, when combined with results of various physiological tests, show 

 that the filaments contain resinous matter in some way suspended in 

 protoplasm. 



The most remarkable point in the behaviour of the filaments is their 

 power of violently contracting. The act of contraction commences by 

 the filament becoming shorter and thicker at a number of nearly equi- 

 distant points, situated close together near the free end of the filament. 

 The curious beading thus produced spreads rapidly down the filament, 

 which ultimately runs violently together into a ball seated ou the top of 

 the gland. In other cases contraction takes place without any previous 

 appearance of beading. 



Filaments frequently break loose but retain their vitality, and are still 

 capable of contraction although separated from their parent glands ; and 

 this observation is of importance, as proving that the movements of the 

 filaments are not governed by forces residing within the glands, but that 

 the filaments are composed of an essentially contractile substance. 



The contraction of the filaments is produced by the following causes : — ■ 



Dilute acids (from 1 to -J- per cent.)— Sulphuric, hydrochloric, acetic, 

 citric, and osmic acids. 



Dilute alkaline solutions Q to | per cent.)— Carbonates of ammonia, 

 sodium, potassium. 



Solutions of gold-chloride | per cent., silver nitrate J per cent., sulphate 

 of quinine T l <j- per cent., citrate of strychnia (about) j per cent., camphor 

 -J^- per cent., the poison of the cobra (about) J per cent., iodine \ per 

 cent. 



Glycerine. 



Methylated spirits. 



Vapour of chloroform. 



Heat. The temperatures at which the filaments contract are rather 

 variable, but are all below 57° 0. 



Electricity. The induced current causes contraction. 



Mechanical stimulation. — The filaments contract when pressure is made 

 on the cover-glass. 



The evidence derived from the experiments, of which the results are here 

 briefly summarized, appears to be strongly in favour of the view that the 

 filaments contain true living protoplasm, and that the sudden movement 

 above described is a true act of contraction ; for if the latter hypothesis 

 is rejected, the only remaining view is that the filaments are so consti- 

 tuted as to be capable of undergoing coagulation, by which contractility is 

 mechanically simulated. But it seems inconceivable that reagents of widely 

 different natures, such as dilute solutions of acetic acid, of camphor, and 



