146 H. J. CONN 



present make this substitution for us, sending crystal violet 

 when gentian violet is ordered. 



The chief cause of variation in results seems to be due to the 

 differences in technic. This shows plainly the need of standard- 

 izing the Gram stain, a task proposed to this committee some 

 time ago. It is hoped as the result of the present work to accom- 

 plish this. Apparently the Stirling technic does not always work 

 with these American products, as they are generally more con- 

 centrated than Griibler's gentian violet. Griibler's stain is 

 well knoT\Ti to have contained a large amoimt of dextrin. The 

 investigators who have used one of the methods calling for a 

 carbolic solution seem to have obtained the best results; although 

 one man who has compared a carbolic solution with the anilin- 

 sulphate solution of Atkins, reports even better results with 

 the latter. 



In conclusion it can be said that several of the American 

 gentian and cr^-stal violets are as good, and some of them better 

 than the Griibler product, when the Gram stain is used as a 

 criterion. It is still too soon to endorse the product of any one 

 manufacturer or distributor, but good results can apparently 

 be coimted on with any of the following : 



Methyl violet 6B Coleman and Bell, Heyl, or H. S. 



Crystal violet Coleman and Bell, Harmer, or Providence 



Gentian violet Coleman and Bell 



It is suggested that anyone wishing to order before definite 

 recommendations are made by the committee specify one of 

 these seven products. 



GENERAL RECOMMENDATIONS 



There is at present so much confusion in this field that the 

 biologist generally has httle idea what actual dye he is buying 

 under any given name. One practice that has contributed to 

 this is that distributors buy the stains in bulk and then repack 

 in small containers bearing their o^v^l label without mention of 

 the name of the manufacturer or standardizer. Sometimes the 

 distributor renames the stain on his own responsibility. There 



