554 MICROBIOLOGY OF THE DISEASES OF MAN AND ANIMALS. 



ing the general metabolism of the cell. In such cases there is a regenera- 

 tion of these chemical receptors by the tissue cells which more than com- 

 pensates for those with which the antigen has combined, and as a result 

 the cell discharges them (chemical substances) free into the body fluids. 



The various antibodies are usually produced more readily by certain 

 tissues than by others. Antibody formation may be of a strictly local 

 character depending upon the point where the antigen is injected. For 

 example, when abrin is placed in the eye, antiabrin is produced, but 

 only in the eye so injected. In the majority of cases the antibodies are 

 produced in some special tissues or tissue at a distance from the point of 

 injection. 



Following the injection of an antigen into the body of an animal, 

 there is always a decrease in the resistance of that body and a decrease 

 in the antibodies produced, followed in a short time by a marked increase 

 in their formation. The former condition is spoken of as the "negative 

 phase" and the latter as the "positive phase." 



Antibodies may be transferred from mother to young before birth, 

 but only after fetal circulation is established. It has been positively 

 demonstrated that antibodies- are not transferred by the ovum or the 

 spermatozoon directly. They are only carried from the blood of the mother 

 and diffused through the placenta into the blood of the fetus. It has, 

 however, been shown that the eggs of immunized chickens contain anti- 

 bodies occasionally. This is " germ-cell transmission" and not true 

 hereditary transmission. The transferred immunity or antibodies do 

 not remain over two or three months in the bodies of the offspring after 

 birth. 



ANTITOXINS. Antitoxins are so called because they combine with 

 and render inert the soluble toxins. Antitoxins are produced for all 

 the bacteria producing soluble toxins and for the toxic substances of 

 a large number of other plant and animal cells. Antitoxins are the 

 free chemical receptors of certain of the cells of the body. That is, 

 they are chemical substances which have been thrown off from the 

 cells of the body and in all probability were normally used for the purpose 

 of taking up food substances. These chemical substances are produced in 

 excess of those actually needed by the cell due to a stimulation of the cells 

 by the toxin. The antitoxins are labile substances which cannot be 

 analyzed. They may be similar to euglobulins. They are composed 

 of molecules of large size. Antitoxins when present in the body of an 



