OCCURRENCE AND FORMATION OF GROWTH SUBSTANCES 69 



and white of egg does not cause increased growth-substance 

 production, but salad oil brings about a decided increase. It 

 would be of interest to investigate auxin content of urine after 

 consumption of Witte peptone, since this substance is an excellent 

 growth-substance former in fungi. KogI and his coworkers 

 assume that 0.1 to 1.0 mg. of auxin is consumed daily in foods, a 

 fact that would explain in part the normal daily elimination of 

 auxin, amounting to 2.0 mg. However, three people showed a 

 daily elimination of 8 to 10 mg. of auxin (Kogl, Haagen Smit, and 

 Erxleben, 1934, Mitt. XI), of which a higher percentage than 

 normal was 3-indole acetic acid. Since this large amount could 

 hardly be supplied by the food consumed, one is led to conclude 

 that the human l)ody must be capable of forming auxin, prob- 

 ably by decomposing or recombining substances supplied with 

 the food consumed. 



SUMMARY 



On the basis of the Avena-coleoptile test, hormones have been 

 demonstrated in many kinds of plants belonging to widely 

 separated taxonomic groups. They have been found in the 

 following higher plants: coleoptiles of Avena, Hordeum, Secale, 

 Triticum, and Panicum; foliage leaves of Nicotiana, Eleagnus, 

 Vicia, Ipomoea, etc.; hypocotyls and stems of Raphanus, Lupi- 

 nus, Vicia, and many others; winter buds of numerous species 

 that are coming out of their dormant period; roots of Zea and 

 Vicia; pollen of orchids. Hibiscus, and Sequoia; fruits and seeds of 

 peas, beans, tomatoes, oranges, lemons, maize, barley, oats, sun- 

 flowers, etc. Growth hormone has been found in the majority of 

 the lower plants that have been tested: among the molds, 

 Rhizopus, Absidia, Aspergillus, Penicillium; in the bacteria, 

 Bacillus, Bacterium, Mycobacterium, Proteus; the fleshy fungus, 

 Boletus; and the alga, Valonia. No doubt, further investigations 

 will reveal the occurrence of growth-regulating substances in all 

 plants. 



The presence of growth hormones in the commercial products 

 of plants has been investigated, and among the materials that 

 have yielded growth substance are malt, flour, and the oils 

 derived from maize, peanut, sunflower, mustard, and flax. 



The richest source of plant-growth substances (auxin a and 

 heteroauxin) has been found in human lU'ine. They have been 



