398 The Physiology of Plants book hi 



may be produced from carbohydrates, and that the latter 

 may be formed at their expense. 



The process of deposition of fat in starved fungi was 

 observed in 1880 by Cunningham. He noticed that as 

 starvation advanced, the protoplasm gradually disappeared, 

 while drops of fat could be seen to form. The fat indeed 

 seemed to be formed at the expense of the protoplasm. 

 Naegeli came to much the same conclusion in 1879, 

 when he determined that its appearance depended but 

 very slightly on the nature of the food supplied to the 

 organism. 



Wakker claimed to have found, in the course of some 

 researches on this subject in 1888, that the deposition of 

 fat is in some cases effected by the agency of plastids, to 

 which he gave the name elaioplasts. He observed them 

 especially in the epidermis of young leaves of Vanilla. 

 They were studied again in 1893 by Zimmermann, who 

 described them as being of various shapes, sometimes 

 round or oval, sometimes very irregular, and lying generally 

 near the nucleus of the cell. They have a structure some- 

 what like that of the chloroplast, consisting of a stroma 

 in the meshes of which the oil is slowly formed. Zimmer- 

 mann found them in the perianth of Ornithogalum and 

 Funkia, and the leaves of a species of Agave, and in the root 

 of Oncidium. 



A passing allusion must be made to the more complex 

 fats and allied bodies lecithin and cholesterin, both of 

 which received considerable attention at the hands of 

 chemists during the last two decades of the century. 

 Lecithin was first found in seeds in i860 by Knop and 

 showed to be of frequent occurrence by Topler in 1861. 

 It is, however, to E. Schulze and his pupils that we owe 

 most of our knowledge of its distribution and of the varying 

 amounts of it present in different seeds. We may associate 

 most of our knowledge of cholesterin and allied substances 



