56 The Precipitins: Methods 



injected. Most workers followed the original method laid down by 

 Tchistovitch and Bordet, injecting what are evidently too large amounts ; 

 others have pursued a course of treatment contrary to what is usual in 

 other immunizations, the dose at the start being as large as that at the 

 finish. Very few appear to have kept accurate records of the weights 

 of their animals during treatment, as given in my paper of VII. 1901, 

 although some state that they were guided to some extent by the 

 variations in weight. It is evident that a more scientific method of 

 treatment has to be worked out, it being, certainly for practical reasons, 

 desirable to discover the least amount of substance which gives a 

 maximum of precipitin, as also the shortest period of treatment 

 necessary. In my protocols (p. 54) the duration of treatment is stated 

 in terms of the number of days intervening between the first and last 

 injection. 



In the preceding table I have summarized the method pursued by 

 me in treating a number of rabbits with different bloods and sera, 

 excluding all the older antisera which were not standardized by my 

 quantitative method, so as to give some conception of the amount of 

 precipitum yielded by antisera obtained in different ways. Owing to 

 other work I have been unable to study this question as I should have 

 desired. The results of Strube, using the intravenous method, had 

 already indicated, what I have also found, that the duration of treat- 

 ment and dosage required are much smaller than when other modes of 

 treatment are used. It is true that my most powerful antisera have not 

 been obtained by the intravenous method, but this is doubtless due to my 

 not continuing the treatment thus begun longer, there being no necessity 

 for doing so, as the antisera obtained were as strong as was desirable 

 for my purposes, quite as strong in fact as some obtained by the other 

 methods. / am certainly inclined, therefore, to accept the intravenous 

 method as being the most advantageous 1 . 



In the experiments by Graham-Smith and Hanger (1903, p. 2(JO), 

 the anti-human serum, and some of the others, were prepared by 

 intravenous injection, but much smaller quantities than those usually 

 employed were found to suffice 3 . " For example 18 c.c. of human serum 

 injected in doses of 5, 5, 5 and 3 c.c. at intervals of 2, 3 and 4 days 

 produced a powerful anti-human serum. The animal was bled 14 days 



1 See further a similar table to mine in the chapter dealing with the experiments 

 of Graham-Smith. 



2 Powerful anti-ox and anti-sheep sera were made by injections of 9'2 and 12 c.c. in 

 doses of 1, 2, 1, 3-2 and 1-5, 2, 2, 3-5, and 3 c.c. respectively. The intervals between the 

 injections were 4, 4, 2 and 5 days in each case, and the animals were bled 7 and 10 days 

 after the last injections. 



