Physiologie der Zellen , Gewebe und Organe. 139 



color of tlie milk fat under equally favorable conditions for the production of a 

 high color. Each breed of cows, however, will undergo the sarne Variation in 

 color of the milk fat which follows a withdrawal or addition of Carotin and 

 xanthophylls, especially Carotin, to the food. Under some conditions also, the 

 apparent breed characteristic largely disappears. Under normal conditions cows 

 of all breeds produce very high colored milk fat for a short time after partu- 

 rition. The pigments of the fat at this time are identical with the normal pig- 

 ments of the fat. Their increase at this time is probably due to the physiological 

 conditions surrounding the secretion of the milk of the freshening animal. 



Pearl. 



347) Palmer, L. S. and Eckles, C. H., Carotin — The Principal Natural 

 Yellow Pigment of Milk Fat. Its Relation to Plant Carotin and the 

 Carotin of the Blood Serum, Body Fat and Corpus Luteum. In: 

 Research Bull. No. 9, Missouri Agr. Exp. Sta., S. 313—336, Apr. 1914. 



In this paper is given a review of the literature on the yellow pigments in 

 the plant and animal kingdom as a preface to reports which are to follow on 

 an investigation on Carotin to show that there is a definite relation other than 

 chemical between the yellow plant and animal pigments. The similarity of many 

 of the yellow pigments found in animals to the so-called Carotins of plants is 

 discussed. It is pointed out that the Classification of the plant and animal pig- 

 ments which is at present generally accepted is to restrict the nanies Carotin 

 and xauthophylls to the two great classes of yellow plant pigments, and to in- 

 clude under the name lutein or lipochrome only those yellow pigments which 

 are considered to be of animal origin. The most recent work in the field of 

 animal chromatology has shown that the luteins can also be subdivided into Ca- 

 rotin and xanthophyll groups depending on their chemical relation to the Carotin 

 or xanthophylls of plant origin. These recent discoveries have opened the way 

 for an extension of such investigations to other yellow animal pigments whose 

 isolation is rendered much more difficult by their association with very large 

 quantities of fat and other substances. These discoveries have also raised the 

 question whether any relation other than chemical exists between the yellow 

 animal and plant pigments. Pearl. 



348) Palmer, L. S. and Eckles, C. H., The Pigments of the Body Fat, 

 Corpus Luteum and Skin Secretions of the Cow. In: Research Bull. 

 No. 11, Missouri Agr. Expt, Sta., S. 392—411, Apr. 1914. 



The results of this investigation show that the yellow lipochrome of the 

 body fat, corpus luteum, and skin secretions of the cow, like the lipochrome of 

 butter fat, is composed principally of a pigment whose physical and chemical 

 properties are identical with the Carotin of green plants. The same pigment may 

 have associated with it one or more minor constituents whose physical and che- 

 mical properties are identical with the xanthophylls of green plants. The Carotin 

 and xanthophyll pigments of the body fat are derived from the food of the cow. 

 The body fat of Jersey cows formed on a ration deficient in Carotin and xantho- 

 phylls, is devoid of color. The body fat of Jersey and Guernsey cows is usually 

 characterized by a higher yellow color than cows of other breeds. This is of 

 great importance in explaining why cows of these breeds may sometimes show 

 a much slower elimination of the pigment from milk fat on a nonpigmented 

 ration, as during the winter months. In these cases the body fat furnishes a 

 supplementary source of pigments for the milk fat. The breeders of Jersey and 

 Guernsey cattle are probably correct in their belief that the yellow skin and 



