286 OF THE BLOOD: ITS VITAL PROPERTIES, 



anthemata and Hooping-cough, we see that it is congenital and is usually 

 removed by the occurrence of one attack of the disease (although this is not 

 a uniform protection); but the liability even to these varies greatly in differ- 

 ent individuals, and at different times in the same individual. And with 

 regard to other zymotic diseases, the liability to which is not thus limited, 

 all extended observation concurs in showing that it is augmented by anything 

 which tends to depress the vital powers of the system, and more particularly 

 by any cause which obstructs the due purification of the blood, by the elimi- 

 nation of the products of decomposition. Thus, it will be shown hereafter 

 (chap, ix, sect. 3), that no antecedent conditions have been found more effi- 

 cacious in augmenting the fatality of Cholera than overcrowding and impure 

 water ; the former compelling those who are subjected to it to be constantly 

 breathing an atmosphere laden with putrescent emanations, thus favoring 

 the accumulation of decomposing matter in the blood, which serves as the 

 most appropriate soil for the seeds of the disease ; whilst by the latter such 

 matter is introduced directly into the system. 1 And what is true of Cholera 

 has been found to be true of Zymotic diseases in general ; the very same 

 fermentable matter in the blood serving for the development of almost any 

 kind of zymotic poison that may be received into the system, whether from 

 the atmosphere, or from the bodies of those who have already been subjects 

 of the disease. That such conditions are constantly present in all large 

 towns is shown in the most satisfactory manner by the observations of Dr. 

 Angus Smith, 2 who found that whilst on the hills above Manchester the pro- 

 portion of organic matter was one grain in 200,000 c. in. of air, in the 

 crowded courts of the town there was one grain in every 8000 c. in., indicat- 

 ing but too surely the source of the various diseases of the lungs, brain, and 

 alimentary canal, which the observations of Dr. Greenhow 3 have shown to 

 occur in such excess in town districts. Hence what has been here spoken 

 of as " fermentable matter," is not a mere hypothetical entity, but has a real 

 material existence ; for in all those conditions of the system in which we 

 know that decomposition is going on to an unusual extent, and in which 

 there is a marked tendency to putrescence in the excreted matters, we wit- 

 ness such a peculiar liability to zymotic diseases, as clearly indicates that the 

 state of the blood is peculiarly favorable to the action of the zymotic poison. 

 This is pre-eminently the case in the puerperal state, in which the tissue of 

 the uterus is undergoing rapid disintegration, its vital force having been ex- 

 pended ; for there is now abundant evidence that the contact of decomposing 

 matters which would be innocuous at other times, is capable of so acting 

 upon the blood of the parturient female as to induce that most fatal zymosis 

 which is known as " puerperal fever." 4 And her peculiar liability is in no 

 respect more manifest than in this: that the poison by which she is affected 

 may have lain dormant for weeks or mouths, for want of an appropriate 



by Dr. W. Farr, has of late gained general currency, for that class of diseases whose 

 phenomena may be attributed to the operation of a morbid poison of the nature de- 

 scribed above; this operation bearing a strong analogy to that of ferments. 



1 See the various papers of Pettenkofer in the Zeits. f. Biologic, 13. v-x. 



- On the Air of Towns. 



3 Papers on the Sanitary State of the People of England, by G. H. Greenhow, 

 M.D., 1859. 



4 For a most marked and convincing example of this kind, see Dr. Routh's paper 

 on The Causes of the Endemic Puerperal Fever of Vienna, in the Medieo-Chi- 

 rurgical Transactions, vol. xxxii, p '27. That the poison which develops puerperal 

 fever may bo conveyed from patients laboring under almost any otheB form of 

 Zymotic disease tending to putrescence, that is propagable by contact, such as 

 scarlatina, small-pox, or erysipelas, is now the general opinion of most pathologists 

 who havo paid special attention to the subject. 



