TISSUE CULTURE 85 



cerous tissue is, as a whole, well differentiated from normal tissue 

 of the type from which it arose, it is not possible to recognize an 

 individual cancer cell under the microscope. A general dis- 

 arrangement of the tissue characterizes the cancerous region, not 

 the individual cells. On the other hand, certain differences have, 

 so it is believed, been found; thus, the malignant cell is generally 

 coarser and more refringent than the normal one. Peculiarities 

 of the chromosomes of cancer cells have been described. In 

 culture, W. H. Lewis finds that all the malignant cells studied are 

 certainly cytologically and culturally differ- 

 ent from normal cells, with a possible 

 exception of the spontaneous adenocar- 

 cinomas of the mouse. The various rat 

 sarcomas and carcinomas are not only dif- 

 ferent from normal but different from one 

 another. So far, says Lewis, no two strains 

 of malignant cells have been found to be p^^, 65.— Tissue from 

 exactly alike. Several different strains of a Hving anesthetized 

 cells cultivated for from one to four years fn^Ta^°o^Stion 'atp^rlffi^^^ 

 have retained their malignancy and their wall, b, follicles, c, nu- 



Cytological and cultural characteristics. %auLgaHnerand PaynZ 



M. J. Hogue has used tissue culture as 

 a means of studying the effects of drugs on cells. Baumgartner 

 and Payne have developed a technique for the study of insect 

 reproductive cells in which certain abnormalities seen in culture 

 do not appear because the body pressure and specific ferments 

 are not disturbed. The technique consists in anesthetizing a 

 male grasshopper and attaching it to a glass slide by means of 

 melted paraffin which is run around the insect so as to form a 

 small chamber in which the grasshopper and salt solution rest 

 (Fig. 65). The preparation may be maintained for several hours. 

 Before the grasshopper recovers from the effects of anesthesia, the 

 testes are drawn out through an aperture in the abdominal wall. 

 The connective tissue, which encloses the tightly packed folhcles, 

 is torn away with a needle, and the follicles float out into the 

 surrounding medium. They remain attached, at the proximal 

 end, to the vasa efferentia and may thus be studied while still 

 connected to the living animal. 



G. C. Hirsch has studied mouse pancreas while it is still attached 

 to the animal. The mouse is narcoticized, and its pancreas so 



