134 THE LYSINS. 



the coloring matter and leave the solution colorless. Of course, in 

 the latter instance, the paper, being smaller, will be more highly 

 colored. Ehrlich has repeated Bordet's experiment with hemolytic 

 serum and blood corpuscles and has not only confirmed his results, 

 but has shown that even a much smaller proportion than one-half 

 the corpuscles will combine with all the intermediary body present ; 

 but his explanation is wholly different from that suggested by Bordet. 

 Ehrlich claims that when half the corpuscles are added to the amount 

 of serum capable of digesting the whole number of corpuscles, each 

 corpuscle combines with a larger number of intermediary bodies than 

 is necessary to effect solution, but the combination having taken place, 

 the intermediary bodies are held and are not free to act upon the 

 corpuscles added in the second portion. Ehrlich states that reactions 

 similar to this are well known in chemistry and he mentions the fol- 

 lowing instance : Naphthalin consists of two benzol rings linked 

 together. If a salt-forming group, a hydroxyl or amido group, be 

 brought in contact with naphthalin, there are formed hetero-nuclear 

 substitution products, such as di-oxy-naphthalin, amido-naphthol, 

 and naphthalin-diamin, whose sulpho-acids are capable of combining 

 with either one or two molecules of a diazo-compound. If two 

 molecules of dioxy-naphthalin be added to two molecules of a diazo- 

 benzol, there is formed exclusively a mono-azo-compound ; but it 

 two molecules of diazo-benzol be added to one molecule of dioxy- 

 naphthalin, there is formed a diazo-compound. If an additional 

 molecule of dioxy-naphthalin be added to the already formed diazo- 

 compound, it is not capable of decomposing this substance ; and the 

 diazo-compound and the unchanged dioxy-naphthalin exist together. 

 We have already referred to the fact that Bordet was the first to 

 show that the addition of a small quantity of normal serum to that 

 of an animal which had been immunized against the cholera vibrio 

 strengthened the bacteriolytic action of the cholera serum. This 

 experiment opebed up the way by which it has been ascertained that 

 there are two factors present in bacteriolytic and hemolytic sera, 

 inasmuch as the normal serum used by Bordet contained the sub- 

 stance which we now designate " the complement," following Ehr- 

 lich's theory. In a second series of experiments, Bordet ^ treated 

 guinea-pigs intravenously with five or six successive injections of 

 10 c.c. each, of the defibrinated blood of the rabbit. From the 

 animals thus treated he obtained a serum possessed of the following 

 characteristics : (1) This serum when mixed with the defibrinated 

 blood of the rabbit agglutinates the corpuscles with great energy. 

 For example, one part of the serum agglutinated all the red blood 

 corpuscles contained in fifteen parts of the defibrinated blood of the 

 rabbit. (2) The serum not only agglutinated but subsequently 

 rapidly dissolved the blood corpuscles of the rabbit. When one 

 ' Annales de I'lnstitut Pasteur, 1898. 



