162 Messrs. H. G. Thornton and G. Smith. 



The facts observed in the culture of Euglena may be summarised as 

 follows : — 



(a) In solutions containing no organic matter, the Euglena increases very 

 slowly. 



(b) By the addition of a trace of organic infusion to the solution of inorganic 

 salts, a good growth of Euglena can often be obtained. 



(c) The efficacy of the natural organic infusion in stimulating the growth 

 was very variable. 



(d) Minute traces of amido-acids added to the inorganic solution had a 

 remarkable effect in stimulating the growth of the Euglena. 



(e) Stronger solutions of amido-acids were less successful owing to the rapid 

 development of bacteria in the medium. 



(f) The Euglena does not appear to live saprophytically on the amido-acid, 

 since it cannot be made to thrive in the absence of light. 



2. Experiments with Soil Protozoa* 



The method of growing Protozoa in solutions containing a mixture of 

 Miquel in tap water to which various organic compounds are added was also 

 applied with a view to studying the protozoal fauna of various soils. 



The mode of procedure was similar to that employed in the experiments 

 on Euglena. The cultures were made in sterilised test-tubes to which the 

 optimal Miquel solution was added, the solutions also being carefully sterilised. 

 Various organic solutions were added to the various tubes, which were 

 inoculated by adding a small amount of soil to each tube. This method was 

 found to be particularly suited to the culture of the minute soil flagellates, 

 more especially Prowazekia terricola described by Martin.f 



The following Table shows a typical series of cultures conducted as 

 described above : — 



* See Dr. Russel and Dr. Hutchison, " On the Effect of Partial Sterilisation of Soil 

 on the Production of Plant Food," 'Journ. Agric. Sci.,' vol. 3, part 2 (1909); also 

 Goodey, 'Roy. Soc. Proc.,' B, vol. 84, p. 165 (1911). 



t C. H. Martin, 'Zool. Anzeiger,' vol. 41, No. 10 (1913). A flagellate monad, similar 

 to that described by C. H. Martin ('Roy. Soc. Proc.,' B, vol. 85, 1912), was found in small 

 numbers in our cultures. 



