3l6 GUY A. VOISIN AND RADSLAV KINSKY 



out of 88 (i 8 per cent) in the facilitated series while it was 3 out of 

 38 (8 per cent) in the non-facilitated series (difference statistically 

 significant). The meaning of these facts will have to be discussed. 

 Finally, it was thought interesting to consider the practical 

 overall results obtained in induction of tolerance during the 

 course of the preceding experiments. 



IV. Practical overall results 



Since it is interesting to know the best way to obtain tolerance 

 (and particularly permanent tolerance) to tissue grafts in a given 

 combination of strains, we have compared the percentage and 

 quality of tolerance induced in A newborn mice injected at birth 

 with CBA normal adult spleen cells and injected at the same time 

 with minute amounts of CBA serum either normal or immune 

 against A antigens. The results are expressed in Table V. 



Table V 



Increase in proportion and quality of tolerance by specific treatment 

 (facilitation) of newborn mice 



Numbers and percentages of mice tolerant and permancndy tolerant as compared to 

 the numbers of mice treated at birth (all survivors were grafted). 



