Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/193

 off, the organ be thoroughly rinsed in distilled water, and boiled over again for ﬁve minutes with not more than ﬁve times its own quantity of water. It is ﬁltered again through a hardened ﬁlter; to 5 c.c. of the ﬁltrate is added at least 1 c.c. of ninhydrin solution, and the mixture is boiled for one minute.

Before the organ is put by for keeping, it is spread upon a white glass plate or a sheet of white paper, and every separate piece is thoroughly examined. Should brown spots or other doubtful points, which cause one to suspect the presence of coagulated blood, be noticed, the pieces affected must be thrown away. Only by conscientiously and carefully adhering to these rules can results be expected which are free from all objection. An organ, which has given a whole series of correct results, may lead us astray if even one single piece containing blood happens to be used.

As soon as the organ has been tested in the above manner for the absence of any piece that may contain blood, and as being free from extractives which react with ninhydrin, it is immediately placed in a bottle, with a well-ground stopper; the bottle having been previously sterilized. Then a little sterilized distilled water and a good deal of chloroform and toluol are added, the bottle being ﬁlled in such a way that the stopper comes into contact with the liquid. A thoroughly well-prepared organ should