Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/205

 The best way is to carry out the boiling in a test-tube for live minutes. It must be boiled energetically, and then filtered through a small hardened filter; after which, at least 1 c.c. of the 1 per cent. ninhydrin solution is added to 5 c.c. of the filtrate. Should one have less than 5 c.c. of the filtrate there is no harm in boiling with 1 c.c. of ninhydrin, because the stricter the conditions of these tests the better.

Boiling is performed (as described on p. 161) for one minute with the aid of a boiling rod. Only in cases, where the solution gives no traces whatsoever of a violet coloration, can the organ be used, and one must wait half an hour before one can establish its presence or absence. Should the organ not be required for immediate use, it must at once be covered with a layer of toluol. Should this test still give a coloration, then the substrate must be boiled over again with five times as much distilled water, until the test shows negative results.

Now, as many standardized dialysing tubes as are required are placed into empty, dry Erlenmeyer flasks, and about ½ grm. of the organ is poured into the tubes. This quantity is previously placed upon a piece of blotting paper, and dried by squeezing it strongly. Were the organ placed in a wet state directly into the tubes, a reaction which would give a weakly positive result might turn out negative,