308 Journal of Applied Microscopy. 



that equally good results may be obtained by the use of 30 cc, in which case one- 

 half of the material may be saved. 



As to the different behavior of phenolphthalein, litmus, methyl orange, etc., 

 with respect to the end-reaction, that is a fact which has been recognized in 

 volumetric analysis for a great many years, although to Mr. Weston it may 

 appear to be entirely modern. My objections to the use of phenolphthalein, 

 based partly upon the interference of organic matter, ammonia salts, and car- 

 bonates, are such as are taught to a beginner in quantitative analysis. It is 

 therefore surprising that Mr. Weston should feel compelled to go back as far as 

 1892, to cite Uahmen as maintaining the same objections as 1 do. If Mr. 

 Weston will consult the various text-books which have been published during 

 the past year or two, he will find that litmus is still used as an indicator, and 

 that in many cases phenolphthalein is not even mentioned. Moreover, he will 

 find in recent American contributions, such as those of Park and his co-workers, 

 that litmus is employed and even preferred by some investigators. A little 

 familiarity with the various European laboratories would likewise teach that 

 litmus has not been superseded by phenolphthalein. 



Mr. Weston also finds fault that, in the preparation of the specific media, I 

 do not specify the optimum reaction for general work. On reference to the 

 article in question (p. 237, 13th line from the bottom), a sentence will be found 

 which Mr. Weston has overlooked, and which explains itself. 



As to the use of the terms broth, broth plus gelatin, and broth plus agar-agar 

 in place of bouillon, gelatin and agar, that is a matter of taste concerning which 

 it is unnecessary to waste words. 



Evidently, Mr. Weston has read my article in a great hurry since he infers 

 that gelatin is added to the broth, and not to the meat infusion. It will be 

 sufficient to refer to the IGth line from the bottom on p. 235. As to my statement 

 that agar dissolves better in clear bouillon than in a meat extract ; this Mr. 

 Weston can readily prove by a comparative trial, but not by an ex eathedra denial 

 based upon the self-complacent attitude that he employs perfect, modern methods. 



Mr. Weston, furthermore, seems to greatly deplore the fact that I should 

 employ other methods than those recommended by the Bacteriological Commit- 

 tee of the American Public Health Association. It is hardly necessary for me 

 to state that I have the greatest respect for the members of that committee and 

 for the work they have done, but as a teacher and investigator I prefer to employ 

 methods which my experience indicates to be the best. These may seem to be 

 empirical to one who possesses the advanced views of Mr. Weston, but neverthe- 

 less they are in accord with the practice that prevails in not a few of the best 

 laboratories in this country and in Europe. F. G. Now. 



The following test for the proteid myrosin is recommended by Gaignard. who 

 finds it in the seeds and other parts of many of the Crueifene: Add one drop of 

 a 10 per cent, aqueous solution of orcin to 1 ccm. of concentrated hydrochloric 

 acid. Heat the sections in this solution to about 100 degrees C. A violet color 

 will appear in the cells containing myrosin. 



