298 GUY A. VOISIN AND RADSLAV KINSKY 



I. Protection against runting 



The occurrence of runting was followed by weight curves and 

 mortahty rate as well as by the well known symptoms charac- 

 teristic of this condition. The percentage of typical runting was 

 found to be particularly high in our experimental conditions as 

 shown by the percentage of deaths on day 3 5 (67 per cent) in the 

 animals of series number 2 (homologous cells plus normal serum). 

 For reasons of convenience, the data concerning the mortahty 

 rates will be presented first, followed by the data concerning 

 weight curves. 



A. Mortality rates 



(i) Overall results 



The results obtained with the various sera, utilized at various 

 doses, once or several times, will be reported first in overall 

 figures comprising all the data. The absolute numbers of deaths 

 as well as the percentages of deaths are determined from the 

 number of animals alive on day 7 after birth. This is the usual 

 way to proceed, owing to the fact that mortality before day 7 

 may be due to several factors other than runting. However, it 

 was found of interest to consider also the figures on day (day of 

 birth and of injection). To do this, the figures concerning day o 

 were plotted against the figures concerning day 7; the day o 

 figures were plotted as negative entities. This was done in the 

 tables as well as in the graphs. The overall figures are sum- 

 marized in Table I and Fig. i. From these, it can be seen that there 

 is a striking and highly significant protection against runting in 

 series i (animals treated with "facilitating" antisera). It can also 

 be seen that this protection consists both in a delayed appearance 

 of runting and in a decrease in the percentage of animals runted. 

 Another point concerns what happens between day o and day 7; 

 it will be considered later. Consideration of Fig. i leads to the 

 observation that protection against runting is maximum between 



