PERFORMANCE OF THE EXPERIMENT 



committed against the fundamental rules of the 

 whole method, that errors are bound to occur. 

 Therefore, we must not ignore a method because it 

 requires careful working. It is quite possible that 

 with time we shall arrive at more simplicity in our 

 manipulations, and technique may place sonic 

 further means at our disposal. But it is as yet 

 too early to try to introduce modifications in the 

 manner of working of the two methods, after a whole 

 number of observers have obtained good results by 

 their means in their present form. The principal 

 requirement of any method is, that we should not rest 

 until the cause of error is found in each case that 

 occurs. This is the only way of avoiding them. 



First of all blood is taken. If there be any doubt 

 regarding the suitability of the substrate it is ad- 

 visable first to test the organ, so as to avoid with- 

 drawing the blood unnecessarily. This test should 

 be repeated immediately before performing the 

 experiment. The blood is allowed to coagulate 

 spontaneously at the temperature of the room. 



Immediately before beginning each experiment the 

 organ is tested, and this important rule must never 

 be neglected. It may so happen that all the parts of 

 an organ have been freed from all extractive sub- 

 stances reacting with ninhydrin, except a piece here 

 or there. It should be the duty of the observer to 

 note down each time in his record : " Organ tested." 



