J38 Physiologie der Zellen, Gewebe und Organe. 



sidered responsible for the mosaic disease of tobacco, parasitisin, in the writer's 

 opinion, offers by far the simplest and most reasonable explanation of its origin. 



Pearl. 



34-5) Whittcii, J. H., The Effects of Kerosene and other Petroleum 

 Oils on the Viability and Growth of Zea Mais. In: Bull. 111. State Lab. 

 Nat. Hist., Vol. X, Art. V, S. 245—272, Oct. 1914. 



The following results were obtained in testing the effect of kerosene and 

 other petroleum oils on the viability and growth of Zea mais: Grains may be 

 immersed in kerosene for periods of ten to twenty days without injury if the 

 optimum conditions for the germination and growth of such grains are provided. 

 These conditions include the removal of the superficial oil from the grains and 

 the presence of a minimum amount of water during germination and initial growth. 

 Injuries which occur to the dry grains immersed in kerosene for longer 

 periods than above indicated are due to the penetration of the oil into the 

 embryos through imperfect membranes. The dry membranes covering the com 

 embryo, wiien perfect, are impermeable to kerosene and to Sudan III. Some 

 grains of Zea mais may be immersed in kerosene for eight years without in- 

 jury to the dormant embryo. The life of dormant grains, with membranes which 

 have been mechanically injured, is destroyed within seventy-five days after im- 

 mersion in kerosene. Kerosene is injurious to the germinating grains in direct 

 proportion to the length of time of immersion and to the increase of the water 

 content of the soil above the minimum required for germination. When moist 

 grains are immersed in a Solution of kerosene and Sudan III, the membranes are 

 penetrated by the kerosene but not by the Sudan III. The membranes are, 

 therefore, semi-permeable. The germinating com grain may absorb and dispose 

 of a limited amount of kerosene without injury. The smaller the amount of 

 water present during germination the larger the quantity of kerosene which can 

 be disposed of. Older com seedlings may dispose of comparatively large quan- 

 tities of kerosene without injury. The injurious effects of petroleum oils on 

 germinating com seem to vary inversely as the volability of the respective oils. 



Pearl. 



346) Palmer, L. S. and Eclvles, C. H., Chemical and Physiological Re- 

 lations of Pigments of Milk Fat to the Carotin and Xanthophylls 

 of Green Plants. In: Research. Bull. No. 10, Missouri Agr. Expt. Sta., 

 S. 337—387, Apr. 1914. 



In this paper the following results are reported on the relations of pig- 

 ments of milk fat to Carotin and xanthophylls of green plants. 



The fat of cows milk owes its natural yellow color to the pigments Ca- 

 rotin and xantophylls, principally Carotin. The Carotin and xanthophylls of milk 

 fat are not synthesized in the cow's body, but are merely taken up from the 

 food and subsequently secreted in the milk fat. When food practically free from 

 Carotin and xanthophylls, such as the cow usually receives during the winter 

 months, is given to a milk-giving cow, the immediate supply of these pigments 

 in the organism is greatly depleted and may be entirely used up, on account of 

 the constant drain upon the supply by the milk glands. If food rieh in Carotin 

 and xanthophylls is given to a milkgiving cow r whose fat has become practi- 

 cally colorless by reason of the above conditions, the organism will at once re- 

 cover its lost pigments and the milk fat will increase in color in proportion to 

 the amount of Carotin and xanthophylls, especially Carotin, in the food. There 

 is some difference among different breeds of dairy cows in respect to the maximum 



