Journal of Applied Microscopy. 307 



This end is not gained best by making up brothi first and tlien adding the 

 requisite amounts of thread agar or sheet gelatin, but by the addition of the 

 thread agar, or slieet gelatin, to the meat infusion at the time when the peptone 

 and salt are added, for when thread agar or sheet gelatin and broth are boiled 

 together for a time sufficient to dissolve the added material, the broth is heated 

 much longer than when nutrient jellies are prepared directly. Nutrient agar can 

 be uniformly prepared without sediment if the modern methods are followed. 



Wh)^ should methods for the preparation of media be uniform ? Why should 

 different laboratories agree in their different methods ? Why should the methods 

 proposed by the Bacteriological Committee be adopted, for the present at least ? 



It must be evident to everyone that comparability of results is desirable, 

 whether the work is done in one laboratory or in several, and the first two 

 questions, therefore, need no comment. The answer to the third question, how- 

 ever, admits of more discussion. This question cannot be better answered than 

 has already been done in the introduction to the committee's report (Journ. Am. 

 Pub. Health Assn., January, 1898). 



These recommendations were formulated by a committee of acknowledged 

 eminence, and for this reason, if for no other, are more likely to be adopted than 

 methods emanating from any single source. Apart from this, the methods 

 recommended have, in practice, proved the most exact and probably, in the 

 broadest sense, the simplest yet devised. The writer does not claim, any more 

 than does the Bacteriological Committee, that these recommendations represent 

 anything more than a basis for uniformity and for future work. 



In view of the fact that so much of the data of the last ten years is in a 

 chaotic condition, largely because of inexact methods and lack of uniformity in 

 technique, it is to be deplored that any teacher with the reputation and standing 

 of Dr. Novy should advocate any set of elementary methods other than those of 

 the Bacteriological Committee which do not, at least, possess distinct advantages 

 over those adopted by the committee. 



It seems unfortunate that Dr. Novy's article, the latest on the preparation of 

 media, should describe methods more like the empirical methods of the earlier 

 workers in Bacteriology than those now accepted as embodying the most 

 advanced views on these subjects. 



Robert Spurr Weston. 

 Boston, Mass., Feb. 28, 1899. 



Reply to Mr. Weston's Criticisms. 



Mr. Weston feels compelled, in the foregoing " Notes," to take exception to 

 the method of alkalization and to the other methods as described in my paper, 

 inasmuch as they " are not based altogether on the modern theory of indicators 

 or on the results of the latest investigations." Some doubt may be expressed 

 as to the exact meaning of the reasons adduced. It may be said that in 

 laboratory work practical results are sought for, and not "modern theories." 



Mr. Weston is' apparently troubled because of the waste of material when 

 60 cc. of the medium are employed to determine the reaction. I can assure him 



