igi2] CURRENT LITERATURE 543 



obtaining it from the organic material in the substratum. This is probably 

 true except for lichens that grow in substrata containing no organic material 

 and perhaps for those having thin cortices. Rosendahl found that thinness 

 of cortex and presence of calcium oxalate go together in the species of Parmelia 

 studied. This would indicate that the algae in lichens with thin cortices 

 obtain their carbon from the air, and so the oxalate is stored in the lichen, 

 while in the lichens with thick cortices the alga secures little or no carbon from 

 the air and utilizes the oxalate obtained from the substratum by the lichen. 

 These investigations of Tobler, Artari, and others prove that we know 

 little regarding the nutrition of lichens and their algal hosts. The results 

 already obtained are important and suggestive. It is to be hoped that much 

 more work of this kind may be done. — Bruce Fink. 



Metabolism of fats, — Ivanow has published a series of papers on the 

 metabolism of fats in higher plants. He emphasizes how little our knowledge 

 has advanced in this field since the classical work of Sachs, and contrasts it 

 with the advances made in our knowledge of protein metabolism in plants. 

 Ivanow 9 believes he has established that the synthesis of fats from glycerin 

 and fatty acids comes about through the reversible action of lipase, a view 

 apparently well established in animal metabolism. 



Another paper 10 deals with the transformation of fats during germination. 

 In order to have seeds with the greatest possible variation in the nature of the 



very 



type: C n H 2 n— tfO 



type: C n H 2 n— 4 2 ), rape (rich in the oleic type: C n H 2 n— 2O2), and poppy (rich 

 in the palmitic type: C n H 2 n0 2 ). In the developing seedling he finds that 

 the intensity of consumption of the fatty acids originating from the fats is 

 inversely proportional to the degree of saturation. The linoleic type of acid 

 disappears first, and with it of course the hexabromide test; then follows the 

 linoleic, oleic, and finally the palmitic types. The fall in the iodine number of 

 the fat during germination is due to the more rapid transformation of the 

 more unsaturated acids to carbohydrates, and not to their saturation by 

 oxidation leading to the formation of acids with shorter chains. The acid 

 number of the fat from each plant is a strictly determined matter, low when 

 the fats are rich in unsaturated acids, and high when rich in saturated acids. 

 If the constituent parts of the oil in a plant are known, one can approximate 

 closely the acid number of that oil. The unsaturated fatty acids are largely 

 tied up in the glyceride, while the saturated acids exist to a larger degree in 

 the free state. The transformation of the oils during germination is by 



9 Ivanow, Sergius, t)ber Oelsynthese unter Vermittlung der pflanzlichen Lipase. 

 Ber. Deutsch. Bot. Gesells. 29:595-602. fig. 1. 1911. 



10 , liber die Verwandlung des Oels in der Pflanze. Jahrb. Wiss. Bot. 



5o:375~386. 1912. 



