METHOD OF STAINING FLAGELLA. 213 



The addition of o"i to 0*2 g. of gallic acid would seem to add 

 to the value of this mordant stain, but excellent results can be 

 obtained without this addition. 



The method we adopt is this : — A drop of sterilised water is 

 placed on an absolutely clean cover-glass, held in a Cornet's clip, 

 and carefully inoculated with the smallest quantity of a twenty-four- 

 hours' agar culture. The cover-glass is moved in such a way that 

 the drop of water is distributed over nearly its whole surface, or a 

 suspension may be made in a watch-glass and a thin film spread 

 upon a cover-glass. It is then placed in the incubator until 

 thoroughly dried (two minutes). A small quantity of the mordant 

 stain is then poured on, and the cover-glass again placed in the 

 incubator for two minutes, or held for that time two feet above the 

 flame of a Bunsen burner. The excess of stam is now washed off 

 by running water, the cover-glass dried in the incubator, and then 

 mounted in Canada balsam. The mordant stain can be used 

 either filtered or unfiltered ; it does not necessarily require to be 

 made fresh each time, as we find that the stain is quite as efficient 

 after a fortnight or so as on the first day of use. The whole 

 process can be accomplished in a few minutes. 



Poisoning by Caterpillars. — Girard, a veterinary surgeon, at 

 Barnewet, has observed numerous fatal cases of poisoning in ducks 

 after eating caterpillars, notably those of Pieris brassicce, the large 

 white cabbage butterfly. About six hours after eating these larvae, 

 poisoning became evident, diarrhoea and staggering grit, followed 

 by dyspnoea, and ultimately death. x\utopsy showed the essential 

 lesions to indicate inflammation of the digestive tube. It is pro- 

 bable that these symptoms are caused by the inflammation pro- 

 duced in the alimentary canal by the very minute hairs with which 

 this caterpillar is covered. It has been noticed that chickens 

 invariably refuse the larva of F. brassicce, although they greedily 

 devoured the smooth larvae of the various Noctua. — Phar. Jour^ 



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