THE AGGLUTININS 223 



circulation, only coming into existence as the blood is shed. If 

 this is the case, it appears clear that its production is not the 

 result of clotting, since -the clumping may occur before coagula- 

 tion has taken place ; indeed, if the blood is carefully watched as 

 it flows from a skin puncture in a marked case of pernicious 

 anaemia, it maybe seen to become " streaky," pale and dark areas 

 being present, and a microscopical examination will show that 

 this is due to clumping of the corpuscles, which thus appears to 

 take place immediately the blood leaves the vessels. 



The researches of Gay would appear to show that the clumping 

 of the red corpuscles by serum is not necessarily due to the 

 presence of an agglutinin at all, but may be caused by variations 

 in the tonicity of the corpuscles and serum. Thus he found that 

 in the bloods which have non-agglutinable corpuscles there is a 

 higher molecular concentration than in the other groups, indicating 

 a greater amount of salts both in the corpuscles and in the sera. 

 There are also differences in tonicity, though less marked, between 

 the members of the other groups. He also finds that if a serum 

 which is hypertonic to a certain sample of corpuscles, and which 

 therefore clumps them, is examined after contact with the 

 corpuscles in question, its tonicity is decreased until it reaches 

 that of the serum which normally accompanies those corpuscles, 

 which, of course, it now no longer agglutinates. This is a simple 

 saturation experiment, the old explanation of which would have 

 been that the agglutinin had all been removed by contact with the 

 corpuscles, but which Gay explains by absorption of salts by the 

 corpuscles. Lastly, a simple hypertonic solution of NaCl and 

 CaCl 2 , and according to Peskind a large number of acids and acid 

 salts, gave rise to appearances suggestive of clumping, though not 

 identical therewith. His researches are highly suggestive, and it 

 may be that we shall have to modify our ideas of the normal 

 iso-agglutinins ; but the subject requires further investigation. 



Rouleaux formation ] presents some resemblances and also some 

 differences. Red blood-corpuscles, when washed free from serum 

 and suspended in normal saline solution, lie free side by side, and 

 show no tendency to run together ; but if placed in human serum 

 and some other fluids, the biconcave discs approach one another in 

 a peculiar orderly fashion, so as to form adherent rolls resembling 



1 I am indebted to some unpublished researches of Dr. Wiltshire's for 

 much interesting information on this subject. Any new fact mentioned is 

 owing to him, unless the contrary is stated. 



