Chapter IV — 27 — Chemical Constituents 



way, in weak chemical combination or by a simple physical adher- 

 ence. These may be disclosed by special histochemical methods 

 isolating them from their combination, i.e., they may be unmasked. 

 Others of these masked lipides are united as stable chemical com- 

 pounds in a very intimate manner with the proteins and can be 

 demonstrated only by destroying the protein substances to which 

 they are united, either by chemical hydrolysis or by digestion. 

 Chemical analysis, therefore, is the only process by 'which their 

 presence can be demonstrated. 



It would seem as if this would hold true for plant cells. It 

 has been observed that tissues rich in proteins are also rich in leci- 

 thins. It is also probable that lecithins are among the most im- 

 portant chemical constituents of the plastids and chondriosomes. 

 Some authors, having ascertained a fixed relation between the 

 content of lecithin and chlorophyll in tissues, state that this pig- 

 ment exists in the chloroplasts, in a combined state, as chloroleci- 

 thin. 



Lipide granules which are found in all cells are perhaps the 

 product of an unmasking of lipides which takes place normally 

 under certain conditions. This phenomenon seems to be more pro- 

 nounced during cellular degeneration resulting in fatty degenera- 

 tion (lipophanerosis) . 



It must be added that Dujardin had observed that when the 

 cuticle surrounding the cellular body of certain Infusoria is injured, 

 the cytoplasm in contact with water forthwith forms droplets which 

 he calls "boules sarcodiques", balls of sarcode. Maggi, who later 

 took up the study of them, thought that they corresponded to the 

 figures observed when myelin (a compound lipide forming the 

 peripheral layer of axone in higher animals) comes in contact with 

 water. There are found then, at the surface of the myelin, fila- 

 mentous protuberances whose extremities finally swell out in the 

 shape of clubs. Many cytologists have found similar figures 

 (KoLSCH, Albrecht, Schneider, Prowazek, Faure-Fremiet, 

 KUSTER) both in animal and plant cells. These figures form in 

 large quantities all around the vacuoles during the phenomena of 

 plasmolysis. They form pedicelled buds which may break off, and 

 become introduced into the vacuole as vesicular buds and might 

 correspond to the myelin figures arising by separation of the lipides 

 from the cytoplasmic lipoprotein compound. 



Various products and mineral substances:- It has been seen that 

 analysis reveals in the cytoplasm, but in smaller quantities, other 

 products of different sorts : sugars resulting from cellular metabol- 

 ism, localized mostly in the vacuoles, and, more important, min- 

 eral substances, among which potassium, magnesium, iron may be 

 especially mentioned. These minerals which seem to play a very 

 important role in the manifestations of living protoplasm, may 

 be in the form of ions or molecules or may be fixed by adsorption 

 to protein substances and enter into the cytoplasmic lipoprotein 

 complex. 



