IRON AND COPPER IN OYSTERS. 29 



Carazzi who is mistaken, as we have found exactly the condition that Ryder describes 



in American oysters {see PI. VI., Fig. 7). 



In connection with this we may state that we have had the advantage of 



discussing very fully the iron and copper reactions, and Carazzi's statements and 



criticisms, with Professor A. B, Macallum, of Toronto, recently in our laboratory. 



Macallum, who is the author of the haematoxylin method of demonstrating iron in 



tissue-cells, agrees with us entirely, and wishes to repudiate Carazzi's remarks in regard 



to the iron reaction 



Finding that we considered it necessary to take notice of Carazzi's papers. Dr. 



Macallum has asked us to insert the following note, which he had already written out 



for publication, as a statement of the method in which Carazzi has misinterpreted and 



misapplied his (Macallum's) and Zaleski's reactions : — 



"In his reference to the literature Carazzi has, in some cases, been particularly 

 inexact. He attributes to Macallum a method of liberating the organic iron of 

 cellular elements (treatment with Bunge's fluid), in order to demonstrate it in the 

 usual way, which that observer not only did not use, but also expressly describes 

 as unsuitable for the purpose. Carazzi obtained negative results only with this 

 method, the only one which he used, and yet he ventures on the basis of results 

 so obtained to deny the correctness of Macallum's observations. In regard to 

 Zaleski, Carazzi is almost equally inaccurate. Zaleski states specially that if the 

 isolated liver-cells are extracted with physiological salt solution, and the residue 

 subjected to artificial digestion after thorough peptonization, nucleins remain in 

 which the iron can be shown ' nicht aber mehr durch die unmittelbare Anwendung 

 der Eisenreagentien,' but after complete incineration only. One nuclein compound, 

 not obtained in this way, did indeed give an immediate reaction for iron ; but 

 Carazzi practically states that all the iron-holding nucleins isolated by Zaleski 

 reacted immediately for iron, and then claims that this accounts for all the iron 

 found in the nucleus by Macallum. An inexact knowledge of the literature on a 

 subject is bad, but a criticism based on it is worse — it is mischievous." 



