234 BERKELEY, ADDRESS AT NORWICH. 



curious contribution to our information on cognate matters 

 has lately been published by Van Tieghem, in which he 

 shows that tannin is converted into gallic acid by the agency 

 of the mycelium of a species of Aspergillus, to which he has 

 given the name of Aspergillus niger. The paper will be found 

 in a late number of the ' Annales des Sciences Naturelles,' 

 and is well worth reading. 



We now come to a subject which is at present of 

 much importance, viz. the theory of Hallier respecting 

 the origin of certain diseases. His observations were at 

 first confined to Asiatic cholera, but he has since made a 

 communication to the authorities of the medioal department 

 of the Privy Council office to the effect that, in six other 

 diseases — typhus, typhoid, and measles (in the blood) , variola, 

 variola ovina, and vaccinia (in the exanthemes) — he has found 

 certain minute particles which he calls micrococci, which 

 under culture experiments give, for each of the above-men- 

 tioned diseases, a constant and characteristic fungus. He 

 states that in variola he gets the hitherto unknown pycnidia 

 oi Eurotium herbariorum ; in yaccinia., Aspergillus glaucus, Lk.; 

 in measles, the true Mucor mucedo of Fresenius ; in typhus, 

 Rhizopus nigricans, Ehrenberg ; and in typhoid, Penicillium 

 crustaceum, Fries. He adds that the culture experiments, 

 especially with the variola diseases, have been so very nume- 

 rous as to exclude from the results all supposition of accident 

 — that different districts, different epidemics, and different 

 times have given identical results. I am anxious to say a 

 few words about the subject, because most of the reports 

 which have been published in our medical journals give too 

 much weight, in my opinion, to his observations, as though 

 the matter had been brought to a logical conclusion, which 

 is far from being the case. I am happy to say that it has 

 been taken up by De Bary, who is so well calculated to give 

 something like a conclusive answer to the question, and also 

 that it has been taken in hand by the medical authorities of 

 our army, who are about to send out two of their most pro- 

 mising young officers, perfectly unprejudiced, Avho will be in 

 close communication, both with De Bary and Hallier, so as 

 to make themselves perfect masters of their views, and to in- 

 vestigate afterwards the subject for themselves. 



The fault, as I conceive, of Hallier's treatise is that, while 

 his mode of investigation is unsatisfactory, he jumjis far too 

 rapidly to his conclusions. It is quite possible that certain 

 fungi may occur constantly in substances of a certain chemi- 

 cal or molecular constitution, but this may be merely a case 

 of effect instead of cause. Besides, as I conceive, the only 



