ZOOLOCY AN it BOTANY, MICROSCOPY, ETC. 191 



other organisms. The Petri dish thus prepared is placed in an incubator 

 at the body temperature, and observations made from time-to time." 



The most effective disinfectants appear to have been carbolic acid 

 and tricresol. 



Purification of Silk Pepton for Bacteriological Purposes.* 

 J. Walker Hall says^that the tetra-peptid sold asisilk pepton has certain 

 advantages for bacteriological purposes over complex mixtures like 

 Witte's pepton. Methods are described for purifying the crude 

 product ; the pigment may be removed by filtration through Argilla alba. 

 The product has the same optical rotation and amino-acid content as 

 that obtained by phosphotungstic acid precipitation. 



Cultivation of Plasmodia of Bodhamia Utricularis.f — A. E. Hilton 

 has found that the growth of a plasmodium of B. utricularis can be 

 stimulated by the occasional application of a mixture of ammonium 

 phosphate and cane sugar, half an ounce of the phosphate and the same 

 weight of sugar being dissolved in a quart of water. 



In rhe second place, he finds that the plasmodium will feed and grow 



Fig. 20. 



on bread kept moistened with water, especially if some of the mixture 

 described be added to it from time to time. 



The effect of the mixture seems to be both direct and indirect. It 

 appears to impart greater vigour to the plasmodium, so increasing its 

 feeding capacity ; and it also benefits the plasmodium indirectly by 

 promoting the growth of filamentous moulds, such as Aspergillus or 

 Penicillium, which soon appear on fungus or bread after the mixture 

 has been applied to it. The hyphaa of these moulds are dissolved and 

 absorbed by the protoplasm as food. 



The author then describes his method of exhibiting the reversing 

 currents of streaming plasmodia.J The very simple arrangement is 

 shown in fig. 20. 



A tube of this size is sufficient, and a ring of blotting-paper, with 

 sclerotium upon it, is placed inside ; the sclerotium being between the 

 paper and the glass. A few drops of water are added, the cork is 

 inserted, and the tube is then tilted and revolved until the water has 

 soaked the paper and moistened the whole of the interior surface of the 

 tube. A small hole is bored through the cork to admit air without 

 allowing too much evaporation ; or the cork may occasionally be 



* Journ. Pathol. 'and Bact., xix. (1914) pp. 286-304; through Journ. Chem. 

 Soc. evii. and cviii. (1915) i. p. 46. 



t Journ. Quekett Micr. Club, xii. (1914) pp. 381-4 (1 fig.). 

 : See this Journal, 1909, p. 196. 



