E. Kindle and Lajos Gozony 
231 
The placenta (or other organs) to be used for this reaction must be 
carefully prepared in order to remove all peptones and other soluble 
materials. First, all the connective tissue and clotted blood are removed, 
and afterwards the organ is cut up into little pieces about 1 cm. across. 
These are then placed into 0-9 per cent. NaCl solution, and pressed 
between the fingers in order to squeeze out all the blood. The salt 
solution is changed until no more blood comes out of the fragments. The 
latter are then washed in tap water for 10 to 15 minutes, and afterwards 
boiled in sterilized distilled water containing five to six drops of glacial 
acetic acid in each 100 c.c. They are then rinsed in cold water and again 
boiled in distilled water—without the addition of acetic acid. When 
the fragments have been boiled five or six times in distilled water, 
changing the water between each boiling, there is a possibility that they 
may have been sufficiently well washed and the next process is to test 
them. For this purpose they are boiled for five minutes with about 
five times their mass of distilled water. Some of this water is then 
filtered, and to 5 c.c. of the filtrate is added 1 c.c. of a Ninhydrin solution 
and the mixture boiled for one minute. After boiling, the liquid is allowed 
to stand for about half-an-hour, and if a blue colour develops it is a sign 
that the tissue has not been sufficiently washed, and it is necessary to 
wash again with boiling water and repeat the process until no blue 
colour is obtained on applying this test. 
By this time Jiiost of the fragments will appear white, but in the 
case of liver, spleen and kidney they are always a little coloured. It 
is better to remove any fragments which are decidedly brown or grey, 
as this is a sign that they contain haemoglobin. 
It is most important that no blood should be left in the organs, as 
the serum often contains ferments having a digestive action upon the 
red blood corpuscles. The serum of quite 50 per cent, of horses and 
cows contains peptolytic ferments that dissolve the red blood corpuscles. 
If any organ therefore still contains red blood corpuscles, a positive 
reaction with serum does not necessarily indicate that any organ destruc¬ 
tion has taken place. For this reason it is advisable, before using the 
prepared organ fragments for any reaction, to test them by adding 
some normal serum and then dialysing in the usual way. The presence 
of peptones in the dialysate, indicated by the Ninhydrin reaction, is a 
sure sign that the organs have not been sufficiently well washed. 
Any pieces of organ prepared in the above manner may be kept 
indefinitely in sterilized distilled water, containing plenty of chloroform, 
with a layer of toluol on the surface of the water. Before using any 
