September 6, 1912] 



SCIENCE 



309 



mones, passed from the reproductive glands 

 into the circulating blood. 



It has been possible in only one or two 

 instances to prepare and isolate the hor- 

 mones of the internal secretions in a suffi- 

 cient condition of purity to subject them to 

 analysis, but enough is known about them 

 to indicate that they are organic bodies of a 

 not very complex nature, far simpler than 

 proteins and even than enzymes. Those 

 which have been studied are all dialysable 

 are readily soluble in water but insoluble in 

 alcohol, and are not destroyed by boiling. 

 One at least — that of the medulla of the 

 suprarenal capsule — has been prepared 

 synthetically, and when their exact chem- 

 ical nature has been somewhat better eluci- 

 dated it will probably not be difficult to 

 obtain others in the same way. 



From the above it is clear that not only 

 is a coordination through the nervous sys- 

 tem necessary in order that life shall be 

 maintained in a normal condition, but a 

 chemical coordination is no less essential. 

 These may be independent of one another; 

 but on the other hand they may react upon 

 one another. For it can be shown that the 

 production of some at least of the hormones 

 is under the influence of the nervous system 

 (Biedl, Asher, Elliott) ; whilst, as we have 

 seen, some of the functions of the nervous 

 system are dependent upon hormones. 



Time will not permit me to refer in any 

 but the briefest manner to the protective 

 mechanisms which the cell aggregate has 

 evolved for its defence against disease, 

 especially disease produced by parasitic 

 microorganisms. These, which belong 

 with few exceptions to the protista, are 

 without doubt the most formidable enemies 

 which the multicellular metazoa, to which 

 all the higher animal organisms belong, 

 have to contend against. To such micro- 

 organisms are due mter alia all diseases 

 which are liable to become epidemic, such 



as anthrax and rinderpest in cattle, dis- 

 temper in dogs and cats, small-pox, scarlet 

 fever, measles, and sleeping sickness in 

 man. The advances of modern medicine 

 have shown that the symptoms of these dis- 

 eases — the disturbances of nutrition, the 

 temperature, the lassitude or excitement, 

 and other nervous disturbances — are the 

 effects of chemical poisons {toxins) pro- 

 duced by the microorganisms and acting 

 deleteriously upon the tissues of the body. 

 The tissues, on the other hand, endeavor to 

 counteract these effects by producing other 

 chemical substances destructive to the 

 microorganisms or antagonistic to their 

 action: these are known as anti-bodies. 

 Sometimes the protection takes the form 

 of a subtle alteration in the living sub- 

 stance of the cells which renders them for a 

 long time, or even permanently, insuscep- 

 tible (immune) to the action of the poison. 

 Sometimes certain cells of the body, such as 

 the white corpuscles of the blood, eat the 

 invading microorganisms and destroy them 

 bodily by the action of chemical agents 

 within their protoplasm. The result of an 

 illness thus depends upon the result of the 

 struggle between these opposing forces — 

 the microorganisms on the one hand and 

 the cells of the body on the other — both of 

 which fight with chemical weapons. If the 

 cells of the body do not succeed in destroy- 

 ing the invading organisms it is certain 

 that the invaders will in the long run 

 destroy them, for in this combat no quarter 

 is given. Fortunately we have been able, 

 by the aid of animal experimentation, to 

 acquire some knowledge of the manner in 

 which we are attacked by microorganisms 

 and of the methods which the cells of our 

 body adopt to repel the attack, and the 

 knowledge is now extensively utilized to 

 assist our defence. For this purpose pro- 

 tective serums or antitoxins, which have 

 been formed in the blood of other animals, 



