160 



Tests tcith Precijnthis 



the precipituni-deficit. He represents this schematically by a figure 

 analogous to the well-known diagrams of Ehrlich, the lactoprecipitin 

 molecule being represented by a circle from which protrude an assumed 

 number (6) of receptors, the majority of which (4) represent specific 

 groups. Whereas the latter are alike, the individual groups (2) are 

 different, and the various combinations of the two lactosera (A and B) 

 and milks (a and h) are thus shown, the precipitable substance in milk 

 being fixed, or not, as the case may be, to receptors. See further under 

 "Individual Differences," p. 145. 



II. Haematosera. 



In the following pages the results of precipitin tests with haemato- 

 sera are given in the zoological order of the antisera, the tests made by 

 other observers being summarized in each case, the results of my tests 

 following. 



The number of tests, made by me with 30 antisera })roduced, is 

 given in the following table, the total number of tests being 16,000. 



Total number of tests 16,000 



In the short tables which follow, I have hriejiy summarized the general 

 results of the tests given in the experimental tables at the end, the object 

 of this being to render the conclusions clearer. The number of sera 



