Notes. 



557 



F. Trypanosoma balbianii Certes. 



The body of Trypanosoma (Spirochasta) balbianii and its un- 

 dulating membrane (especially the " bordering filament ") give a 

 feeble reaction between crossed nicols. This illumination is due 

 to depolarisation, and disappears in a liquid with an index 

 N L = 1 • 56 :— 



That the illumination of T. balbianii should be of this kind is 

 not without interest, in view of a recent discussion on the nature 

 of the " strengthening striations " of its membrane. These stria- 

 tions were regarded by Vies (1906) as of a ciliary nature — an 

 opinion which was rejected by Borrel and Cernovodeanu (1907), 

 and finally by Fantham (1908), who would have them to be 

 myonemes. The optical properties that we have just described 

 seem rather in favour of the first theory ; their illumination being- 

 due to depolarisation, removes these elements from among the 

 myonomes ; further, their "index of extinction," close to 1*56, 

 possibly places them nearer fiagella than cilia. 



Conclusions. 



The results of all these experiments, as well as of the former 

 experiments by Vies, may be summed up thus : the reactions of 

 contractile organs between crossed nicols permit of their being 

 divided into two groups, of which one is characterised by true 

 birefringence, and the other by phenomena of depolarisation. These 

 two groups are indicated by the following table : — 



Illumination due to 



Birefringence 



Depolarisation 



Muscle-fibres. 

 Myonemes of Protozoa. 



Epithelial cilia. 

 Cilia of Protozoa. 



„ Ctenophora. 

 Fiagella of spermatozoa. 

 Body and undulating membrane 

 of Trypanosoma balbianii. 



