80 The Patliological Relations of the 



inflammatory affection of the throat. Consequently a considerable 

 confusion of thought as well as of language even now exists 

 among medical men on the etiology of the affection diphtheria ; 

 and it has been asserted, only quite recently, that nothing more 

 than " a clinical tradition " separates diphtheritic and croupous 

 complaints ; indeed, it is boldly stated and taught, both in this 

 country and on the Continent, " that croup, accompanied by false 

 membrane in the larynx and trachea, is always a diphtheria, 

 whether in the child or in the adult."* And again, " that while 

 both diseases are highly contagious and inocuable, they are one and 

 the same disease, neither peculiar to children nor adults, as they are 

 equally sporadic, epidemic, and endemic."t My answer to this 

 statement is, that while one disease, diphtheria, is most decidedly 

 epidemic and endemic, often widespreading and affecting a large 

 proportion of adults, and probably belonging to a specific form of 

 fever ; the other, croup, is essentially sporadic, often a local affec- 

 tion, not communicable, or only so in a small degree, as when a 

 family predisposition exists, mostly occurring during childhood, 

 and rarely after it is fairly passed. The contradictory evidence of 

 clinical medicine compels us to put it aside, and look entirely to 

 histological anatoniy for a solution of the difficulty raised by the 

 physician. I maintain that a sharp line can be drawn between the 

 diphtheritic membrane and the croupous cast, and surely if this 

 be demonstrated, no one will venture to say that " clinical tradi- 

 tion " alone separates diphtheria and croup. I will first glance at 

 the naked eye appearances of the diphtheritic membrane. As the 

 name implies, it is a dense, compact, opaque, yellowish-white or 

 reddish-grey coloured mass, of from half a line to five or six lines 

 in thickness. It is usually firmly adherent to the subjacent mem- 

 brane, upon which it is moulded ; is more or less friable, so that 

 when traction is made upon it with a pair of forceps it comes away 

 piecemeal, or in a layer somewhat resembling felt or chamois 

 leather. If forcibly detached, a breach of continuity of surface is 

 made, and bleeding generally follows its separation, as the mucous 

 membrane is much congested. Frequently general tumefaction 

 from excessive corpuscular infiltration occurs, and then compression 

 of the vessels, and an arrested circulation, ends in decomposition. 

 Ulceration of the superficial and deeper-seated structures produces 

 paralysis of the nerves, probably of the vagus, and quickly kills the 

 patient. By no unaided effort on the patient's part during the 

 extreme paroxysm of the attack is the membrane ever thrown off. 



In striking contrast to the foregoing brief description of 

 diphtheria and its membranous exudation, the croupous cast is 

 semi-transparent, delicate, and tender to handle; often gelatinous 



* Sir Thomas Watson's ' Practice of Physic,' vol. i., p. 903, 1872. 

 t Prof. M. Roger's ' Chemical Lectures,' 1872. 



