248 



the culliirc. containin<:j Iho lillle frafrmenl of normal mus- 

 cular tissue and the sarcoma has to hv renewed and trans- 

 ferred, the two fragments arc picked u|) on the point of Ihe 

 needle or knife from the liquefied medium, washed in Hi n 

 ger solution and replaced in a fresh culture medium. After 

 a few passages, the two fragments generally adhere to each 

 other and can be transferred as one piece. 



After about 4 — passages the muscular tissue is perfectly 

 destroyed and a new piece must be added. Before the mus- 

 cular tissue is destroyed and completely invaded by sarcoma 

 cells, the total mass of tissue can be divided and subcultures 

 made. 



When a small fragment of the Rous chicken sarcoma is 

 cultivated in the usual way in chicken plasma and em- 

 bryonic tissue juice, an extensive litpiefaction takes i)lace in 

 the surrounding medium within few hours, and the fragment 

 is found after 24 hours to be floating in the medium sur- 

 rounded by numerous spherical cells. After a few passages, 

 the fragment becomes smaller and smaller, and dies. The 

 liquefaction of the culture medium prevents actual increase 

 of the mass and the tissue cannot be divided and the cul- 

 tures multiplied, as can be done with the fibroblasts and 

 epithelium. On adding a piece of solid muscular tissue to 

 the sarcomatous tissue in the culture, the sarcoma cells are 

 observed to migrate abundantly to the muscle before any li- 

 quefaction of the medium has taken place. After the li- 

 quefaction has begun, many cells have already migrated over 

 in the muscle where they multiply very extensively, inde- 

 pendently of the liquefaction going on. 



After a few passages, sometimes already after the I'ii'sl 

 passage, the normal muscle fragment and the sarcomatous 

 tissue adhere to each other, so they can be transfeiTed as 

 one piece of tissue. After 2 — 4 passages, the muscular tis- 

 sue is so invaded by sarcoma cells, that it can be separated 

 from the original tissue and li-ansferred to a separate cul- 

 ture, where it is able to grow independently and behaves ex- 



