240 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Mycetozoa.* — Under the title The Mycetozoa and some Questions 



which then suggest, Sir Edward Fry and Miss Agnes Fry have brought 



out a very useful little account of the structure and. mode of propagation 



of the Myxomyoetes, together with some speculations as to their place 



in nature. 



Protophyta. 



a. Schizopliycese. 



Pleurococcus and Pseudo-pleurococcus.t — Prof. E. Chodat dissents 

 from the conclusion of Dr. Julia W. Suow that the two forms described 

 by her should be regarded as types of a new genus Pseudo-pleurococcus, 

 They are but varieties of Pleurococcus vulgaris. 



#. Schizomycetes. 



Duration of Bacterial Existence.^— Dr. H. L. Bolley records some 

 interesting observations on the vitality of bacteria. Agar tube cultures 

 were hermetically sealed up above the slant and kept for some years 

 (1-9) before they were opened and tested as to viability. The obser- 

 vations show that even non-sporing bacteria may retain not only their 

 fresh appearance and normal morphological characters, but also their 

 viability, for a number of years. Even when dead, the germs were not 

 disintegrated. The non-disorganisation of living or possibly dead germs 

 in a moist organic substratum, and in the probable absence of oxygen, 

 is a highly important observation. The results are given in detail in 

 tabular form. 



Reducing Power of Bacteria. § — Dr. F. Midler has amplified his 

 previously recorded experiments and observations on the reducing power 

 of bacteria by using acetate of rosanilin in addition to methylen-blue 

 and litmus, and increasing the number of bacterial species. The results 

 do not differ materially from those previously recorded, and may be 

 summarised as follows. The pigments to be used for demonstrating the 

 reducing properties of bacteria should be of known composition, and the 

 behaviour of the medium should be previously ascertained ; e. g. while 

 agar exerts a considerable reducing action, that of bouillon is slight. 

 It was found that ordinary test-tubes gave better results than fermentation 

 flasks for observing the reduction. The reduction of the pigment is 

 due to the metabolic products excreted by the bacteria, and takes place 

 outside the bacterial organism. These products of metabolism exert a 

 reducing action, not only directly after excretion, but even after consider- 

 able lapse of time ; they are however gradually destroyed by atmospheric 

 oxygen. All bacteria are capable of reducing suitable pigments ; as the 

 excreted reducing substances are apparently of different nature, the re- 

 duction processes may be determined not only quantitatively but quali- 

 tatively. Many bacteria are able to incorporate pigments ; those which 

 form pigment do not as a rule show that they pick up pigment from the 

 medium, e. g. B. anthracis, hay bacilli, and Proteus. 



* ' The Mycetozoa and some questions which they suggest,' London, 1899, viiu 

 and 82 pp. and 22 figs. 



t Bull. Herb. Boissier, vii. (1899) pp. 827-8. Cf. this Journal, 1899, p. 634. 



: Central!)]. Bakt. u. Par.. 2* Abt., vi. (1900) pp. 33-8. 



§ Op. cit., 1" Abt., xxvi. 1899) pp. 801-19. Cf. this Journal, 1899, p. 634. 



