Direct Matching of Bloods 



469 



test tube showed that moderate agglutination of P. L. corpuscles 

 was produced by as little as 1/20 volume of the M. plasma. 



This observation reveals a risk in using a member of the 

 so-called "Universal Donor" group for the first time without 

 making a rough quantitative examination of the agglutinating 

 power of the individual's plasma. It is advisable, therefore, in 

 carrying out the direct matching according to Coca, to include a 

 mixture of equal parts of undiluted recipient's citrated blood 

 with the donor's citrated blood, diluted 1 to 5. 



232 (2192) 



Application of the murexide test to Amoeba verrucosa and 

 Paramecium caudatum. 



By RUTH B. HOWLAND (by invitation). 



[From Cornell University Medical School, New York City.] 



Observations made on the distended contractile vacuoles of 

 Amoeba verrucosa subsequent to the application of the murexide 

 test give no optical evidence of the presence of uric acid in the 

 vacuolar fluid. This result is not in accord with the generally 

 accepted conclusions of Griffiths 1 who reported the production 

 of "prismatic crystals of murexide" on application of this test 

 to Amoeba proteus, Vorticella and Paramecium. Mass cultures 

 of Amoeba verrucosa, killed in 50 per cent, alcohol, show the 

 contractile vacuoles fixed at partial or complete expansion in a 

 large percentage of cases, but a critical examination of the fluid 

 of the vacuoles has never revealed the presence of uric acid 

 crystals precipitated there by this method. Dark field examina- 

 tion of such animals shows the fluid to be structureless. Treat- 

 ment with nitric acid and ammonia in the manner described by 

 Griffiths colors both cytoplasm and pellicle a lemon yellow. 

 Furthermore, control slides, consisting of a small quantity of 

 pure uric acid crystals in distilled water, when similarly treated, 

 also give a negative result. Such controls give ammonium pur- 



1A. B. Griffiths, Proc. Soc. of Edinburgh, 1888-89, rvl 



