169 



In order lo get a better technique and more accurate 

 information as lo the function of such rhytmical cell 

 division, another method was appHed. Series of photomi- 

 crographs were taken of parts of the peripherial line of 

 growing fibroblasts in the culture. 



Table 12. 

 Experiment No. 460 and 461. 



No 



Total number 



of mitosis 

 in peripliery. 



Total number 



of cells 

 in periphery. 



Percent of 

 mitosis. 



460—1 

 460—2 

 460—3 

 460—4 

 460—5 

 460—6 



461—2 

 461—3 

 461-4 



8 

 8 

 6 

 9 

 14 

 9 



3 

 2 



4 



Average: 1,3 



Ttiis table shows the total number of mitotic figures found in 

 cultures of fibroblasts, fixed and stained. The mitotic figures 

 among the cells representing the total line of periphery of tlie 

 culture can be seen. Cultures Nos. 460—1—2 — 3—4 — 5 and 6 are. 

 made from one culture. The cultures Nos. 461—2—3 — 4 are also 

 made from one culture. 



Nos. 460—1 and 460—2 were taken out from the incubator 

 at the same lime and fixed immediately. Half an hour later Nos. 

 460—3 and 460 — 1 were taken out and fixed. In another half 

 hour Nos. 460 5 and 460—6 were taken out and fixed. An liotir 

 later Nos. 461—2, 461—3 and 461 — 1 were fixed. 



The technique was simply this. A culture of fibroblasts 

 was incubated for about 24 hours and thereafter placed 

 under the microscope, kept at a temperature of 39° C. The 

 size of the photographs was 4,5 by 6 cm. and were taken 



