74 COAL-TAB COLORS USED IN FOOD PRODUCTS. 



2. Is the usual answer which is given to the hygienist by the defenders of the unre- 

 stricted use of the coal-tar dyes for coloring food products and beverages, namely, that 

 in practice the dyes are introduced into the human organism in so small quantities 

 that their properties can be neglected, justified? 



To both questions, besides the facts and considerations which I gave above in my 

 investigations, we may reply experimentally in two ways: 



(a) By prolonged investigations continued over a period of years of the action of 

 very minute quantities on the animal organism, which has so far, owing to the incon- 

 veniences of such long experiments, not been done by anybody; and 



(6) By investigation of the action of small doses of dye on some physiological func- 

 tions, and first of all on the activity of the digestive organs, which is first of all dis- 

 turbed upon the introduction of dyes into foods and beverages. The solution of the 

 last question can be best promoted, in my opinion, by experiments made on dogs and 

 by exploratory examination of the body according to the method of Prof. Pawlow. 

 Unfortunately, experiments such as these, owing to the difficulty of the Heidenhain- 

 Pawlow operation, are inaccessible to the majority of investigators. 



As a very useful substitute of such investigations may serve observations on the 

 action of dyes on the activity of the digestive juices outside the body of animals. 



On my proposition Dr. A. E. Winogradow began in my laboratory experiments on 

 the action of small doses of dyes of the aromatic series on the digestion in vitro. Drj 

 Winogradow so far examined 25 coal-tar dyes in this respect according to the method of 

 Metta and convincingly proved that in insignificant doses coal-tar dyes (from one-half 

 to 4 milligrams) entirely stopped the digestion of albumen by artificial gastric juice. 

 It was found that the capacity to depress the digestion is possessed not only by poison- 

 ous dyes, but also by dyes which proved in my experiments on animals nonpoisonous. 



It is quite possible, therefore, that an admixture of coal-tar dyes will exert an unfa- 

 vorable influence on the digestion and assimilation of food prepared from products col- 

 ored by them. Experimental proof of the last supposition can be given only by experi- 

 ments on the influence of dyes on the metabolism of substances in animals and man. 



COMPLETE DETAILED STATEMENT OF ALL COMBINED DATA. 

 ABBREVIATIONS OF AUTHORITIES CITED. 



The data hereinafter given is brought together as nearly as pos- 

 sible under the Green Table numbers to which it is pertinent. It is 

 believed that the literature has been quite thoroughly searched, and 

 that nothing of substantial importance has escaped recording in this 

 compilation; certainly whatever may have escaped can hardly serve 

 to change the general conclusion to which this compilation leads. 



In order to avoid repetition in the following tabulation, "Weyl" 

 is to be understood as referring to the book entitled "The Coal Tar 

 Colors, with Especial Keference to their Injurious Qualities, etc./' by 

 Theodor Weyl, translated by Leffmann and published in Philadel- 

 phia, Pa., in 1892. 



"Lieber" refers to the book entitled "The Use of Coal Tar Colors 

 in Food Products," by Hugo Lieber, published in New York in 1904. 



"Fraenkel" refers to the book entitled "Arzneimittel Synthese," 

 by Dr. Sigmund Fraenkel, published in Berlin in 1906. 



" Confectioners List" refers to the Official Circular from the Exec- 

 utive Committee of the National Confectioners' Association of the 



