7 
the year 1689. It was described by Sydenham and Morton. All the early 
physicians who wrote on the disease considered it to be only a modification 
of Measles. This confusion prevailed, more or less, down to the end of 
the last century. 
These two diseases show the same general resemblance during their early 
stages as Measles and Small Pox. I have seen, at an early stage of 
Scarlet Fever, the eruption on the arms assume the crimson appearance of 
Measles^ and the diagnostic differences have not been pronounced until a 
late period. But what makes this point intensely interesting is the 
existence of an important member of the group, which is as a bond of 
union between the two, showing the very links of development, as it were, 
which are so often lost in natural history, I allude to a small Exanthem 
which I have called according to the German writers, Rotheln. It has 
been described by different writers under the names Morbilli, Roseola, and 
other names. One of the best and latest textual writers on English 
medicine describes it very unphysiologically as a hybrid of Measles and 
Scarlet Fever but it does not protect the system from either of those 
diseases, nor do they in turn afford the least XDrotection against it. 
Describing the disease as it suddenly appeared before me in this city two 
years ago, — it begins with the general symptoms of Measles, the 
countenance is suffused and the eyes watery, with the cough so character- 
istic of that disease an eruption precisely like Measles appears on the face; 
on the second or third day this fades and a pure scarlatinal eruption 
appears on the trunk and extremities; so exactly does this resemble 
scarlatina, that when it appeared in a member of my own family who had 
previously had scarlatina, I pronounced it to be a modified form of that 
disease ; in this opinion I was confirmed by an experienced member of the 
profession. The symptoms rapidly vanished leaving not a trace of any 
evil behind them. Finding a similar affection prevalent in the city a light 
soon broke on me that I had to do with the German Rotheln. Every case 
could be traced to infection from another. Now I almost fancy that here 
we have the prototype still existing alongside of its two gigantic and 
powerful offsprings, viz., Measles and Scarlet Fever,* compared with 
* There are several small Exanthems circulating around Measles and 
Scarlet Fever as there are known to be three or four around Small Pox. 
I have taken Rotheln as typical of the former group, and Varicella of the 
latter. From the exemption of many persons from the infectiousness of 
Scarlet Fever I surmise that one of the former group is of the same 
species as, and protective from, Scarlet Fever. The discoverer of this 
valuable Zymotic Asteroid would acquire the fame of Adams, Leverfier, 
and J enncr combined. It exists : What is it ? 
