INFECTION. 77 



lie somewhat beneath the general level of the pleura. This is real- 

 ity atelectasis pulmonum, that is, airless. The structural changes of 

 the lung by which this condition and true collapse are produced 

 are absolutely different. In atelectasis we have a shutting off of the 

 supply of air, a gradual absorption of that which was present, and 

 a consequent retraction of the pulmonary tissue, by which the blood- 

 vessels come nearer together ; a non-oxidation of the blood in the 

 same, hence the darker color ; but the lung-tissue retracts, it retains 

 its elasticity. In collapsus pulmonum the lung-tissue has lost its 

 elasticity, an entirely different condition. Such a lung has lost all 

 the springy characteristics of normal lung-tissue ; it is dead, doughy to 

 the touch, which is never the case in atelectasis. Again, clinicians 

 speak of hepatization, instead of solidification or infiltration of the 

 lung. Hepatization means, indeed, solidified (liver-like), but only to 

 the touch. The observation and language of the dissection-table have 

 been transferred to the bedside, where they do not belong. Each 

 place has its appropriate language. 



We speak of apoplexia cerebri, as if there were no other form of 

 apoplexy, whereas the word means to strike down, to cease acting 

 suddenly; hence we may also have apoplexia cordis, pulmonum, 

 laryngia, medulla oblongata, all organs the continual action of 

 which, or of parts of them, are absolutely necessary to the continu- 

 ance of life. We here again mix up cause and effect. Apoplexy 

 is the cessation of function, not the cause. The haemorrhages in 

 the brain are that and nothing more ; but because in some cases 

 apoplexy accompanies them, they are not always apoplectic centers. 

 The part complicated, or the amount extra vasated, causes the clinical 

 expression apoplexy. 



While these things have, as it were, become sanctified by usage, 

 they are not in accordance with the logical use of language. 



Concussion of the brain, by which life ceases, may be supposed 

 to take place without haemorrhage, yet is essentially apoplexia cere- 

 bri, though we never hear it spoken of as such. 



With reference to some of the infectious, or, better, contagious 

 diseases, we find medical writers falling into the same error when 

 they speak of the elements by which the disease is transmitted to 

 human beings as "animal poisons." There are animal poisons, 

 such as come from reptiles ; but the infectious elements of the con- 

 tagious diseases are not, logically speaking, poisons. 



A poison is something which in well-defined quantities causes 

 specific effects. Unless this quantity of a given poison is intro- 

 duced into the system, this effect does not follow. 



