434 WAEREN H. LEWIS 



and concentrically in another type. The mitochondria are sup- 

 posed to be a combination of phospholipin and albumin."^ Many 

 histogenetic functions have been ascribed to them, such as the 

 formation of neurofibrils, myofibrils, collogenic fibrils, etc., 

 there is, however, reason to doubt even the existence of such 

 fibrils in living cells, and more doubt still as to whether the mito- 

 chondria take any especial part in their formation. The mito- 

 chondria are probably concerned with functions more general in 

 nature, such as respiration, storage of food stuffs or waste prod- 

 ucts, etc. We are not sure that they are to be considered as 

 part of the living cytoplasm; they may be merely cytoplasmic 

 inclusions, dependent for their existence on the activities of the 

 protoplasm. 



In cultures over twenty-four hours old practically all of the 

 cells contain granules that take up the neutral red dye with 

 great avidity and tend to accumulate about the centriole and 

 centrosphere. Vacuoles which likewise take up the neutral red 

 dye are found in the cells, especially in the older cultures; they 

 also tend to accumulate about the centriole and centrosphere. 

 Since they occur in degenerating cells, we have called them 

 degeneration granules and vacuoles. It is not uncommon to 

 find slender channels, much the same in size and shape as mito- 

 chondria, connected with the vacuoles. These channels are 

 very unstable — they come and go and often anatomose. They 

 take up the neutral red, methylene blue (Ehr.), and brilliant 

 cresyl blue in exactly the same manner as do the vacuoles, and 

 are therefore to be regarded as merely extensions of them. I 

 have looked upon the granules and vacuoles as indicating degen- 

 erative changes^ in the cell, in that they probably represent 

 accumulated waste products which the cell is unable to get rid 

 of in the normal manner. The vacuoles may indicate also that 

 there has been a certain amount of autolysis of the cjrtoplasm. 



^ Cowdry, E. V. 1918 The mitochondrial constituents of protoplasm. Con- 

 tributions to Embryology, VIII, Carnegie Institution of Washington, Pub. no. 

 271. 



^ Lewis, W. H. 1919 Degeneration granules and vacuoles in the fibroblasts 

 of chick embryos cultivated in vitro. Johns Hopkins Hosp. Bui., vol. 30. 



