oKSERVATioxs o\ filart.t:. < i 



blamed, I think, unfairly, by Dr. Magalliaes in his paper in last 

 number of the " Gazeta Medica." 



Dr. Magalhaes, in that, as in his former paper, charges me with 

 calling in question what had been observed by others, notably by 

 Dr. Lewis and himself, for no other or better reason than that I had 

 not been able, as he surmises from inadequate methods, to confirm 

 myself the truth of those observations. 



Now, as I have already explained, I never called in question any 

 observation ; what I called in question was the interpretation of an 

 observation, plain and palpable and common to all of us. 



My method for the microscopic examination of Filaria, Dr. 

 Magalhaes finds antiquated. How he came to know my method is 

 to me a mystery ; for in no communication of mine have I ever 

 so much as alluded to that subject. When 1 spoke of the state of 

 the blood on the slide at the end of five hours, I spoke of that state 

 as the context, and the whole scope of my argument showed, not as 

 seen in any original observations of my own, but as seen in those of 

 Dr. Lewis, or of any one else, repeating those observations, accord- 

 ing to the method emi^loyed and described by Dr. Lewis himself. 



With Dr. Magalhaes' permission, I therefore pass on the cap of 

 antiquity to Dr. LcAvis, for whose head, and not for mine, it must 

 have been intended. While on this subject, Dr. Magalhaes, who 

 appears to take an unwonted interest in my scientific education, will 

 be glad to learn that, even before his very lucid hints, I had already 

 acquired some elementary notions of the possibility and the means 

 of retarding or diminishing the natural plasticity of the blood, and 

 had turned that knowledge to account so far, at least, as to prolong 

 on the slide the life and movements of Filaria, and my observations 

 on the same, to periods frequently extending beyond 24, and not 

 rarely beyond 36 hours. 



In Dr. Lewis' opinion, no difficulty ought to be encountered by 

 any one in detecting the involucrura, as he had never himself failed 

 to do so in thousands of cases, and affirms that the only requisites 

 for the purpose are a good microscope and properly-adjusted illumi- 

 nation. This assertion of Dr. Lewis I can fully bear out ; never, 

 with all thie mal addresse with which I am so liberally credited by 

 Dr. Magalhaes, having once failed, if not in thousands, at least in 

 many scores of eases, to detect what Dr. Lewis calls — and what 

 under protest, I am content to speak of as the involucrum, when, 

 looked for at the time, and with the slide prepared as Dr. Lewis 



