Experimental Growth in Anin^als 247 



Bone repair has been studied in rabbits. i" The tibia was cut 

 transversely, without damaging the periosteum otherwise than locally. 

 Mitoses were coimted from day to day, the animals being killed 9 to 

 10 hours alter 0.625 mg/kg of colchicine. The amplification of the 

 mitotic changes made estimations of relative growth far easier than 

 in control animals (Fig. 9.16). 



PERIOSTEUM 



. , ENDOSTEUM 



. ^ ENDOTHELIAL CELLS UPERlOSTEUM 



HIST?OCYTES J I ENDOSTEUM 



days: 



Fig. 9.16 — Repartition of mitoses during bone repair, studied after injection of colchicine. 



(After Borghetti and Parini') 



These few papers have studied only some limited aspects of heal- 

 ing and inflammatory reactions. Here again, large fields remain open 

 for investigation, and it is surprising that more work has not been 

 completed. 



9.7: The Action of Chemicals on Mitotic Growth 



Few papers have been published in this section, a surprising fact, 

 for colchicine could no doubt help in the study of many substances 

 affecting growth. In work on vitamins, for instance, many experi- 

 ments could be imagined. Some results with folic acid antagonists 

 will be mentioned in Chapter 10. 



The possibilities of finding new facts is illustrated by the follow- 

 ing experiments: Young rats were intoxicated with carbon tetrachlo- 

 ride and studied at various intervals by a routine (olchicine technique 

 (Fig. 9.17). Arrested mitoses were observed in the liver cells and in 



