84 PROTOPLASM 



serum obtained from a fourteen-months'-old infant, and the 

 other half with serum from a twenty-seven-year-old adult. The 

 cultures treated with the infant's serum attained an area in ten 

 days which was over 150 per cent greater than that reached by 

 those treated with adult serum. 



Finally, there is the ever present and tragic story of cancer. 

 Fischer has placed cultures of cancerous and normal tissues side 

 by side and watched how the cells of the former penetrate the 

 framework of the latter. Carrel, Baker, and Ebeling have found 

 that glycocoU increases the rate of growth of sarcomatous (cancer) 

 cells about 70 per cent. If it is glycocoll that causes unlimited 

 growth of cancer cells in our bodies, perhaps the growth could be 

 checked by control of excessive glycocoll production. 



There is one possible criticism of tissue culture as a method of 

 cancer study. Cells growing in a drop of solution on a glass 

 slide in an incubator are in an environment which, although in 

 many respects like that in the body, is nevertheless an artificial 

 one. There is no blood stream, no nervous system, no coordi- 

 nated body. Will the culture cells, therefore, remain identical 

 with others of their kind within the organism? In certain 

 respects they do, but many differences exist, and one of the most 

 significant of these is that tissue cells, like cancer cells, grow on 

 indefinitely. Normal body cells grow until a mature organ is 

 formed and then stop. Only abnormal cells, such as those of a 

 tumor, grow on and on. They lack a "purpose" in life. Such 

 lawless growth is also characteristic of cells in tissue culture. 

 This leads one to suspect that cells in culture possess a type of 

 abnormality like that of tumor cells. The persistence in type 

 shown by some cells in culture is evidence against this criticism; 

 cells in tissue culture do adhere to certain heritable tendencies 

 and do not become wholly abnormal. 



Some interesting and important bits of evidence support the 

 foregoing statement that cells in culture retain certain of their 

 original characteristics over a long period of time; thus, cancer 

 cells in culture will produce cancer in an organism inoculated with 

 them some months after the culture is started, while normal cells 

 in culture never acquire this property. 



Culture methods also throw light on the much discussed prob- 

 lem of the possible morphological distinction between normal 

 and cancerous cells. It is maintained by some that while can- 



