POSTIRRADIATION TREATMENT OF MiCE AND RaTS 149 



tissues have been examined cytologically by Ford and 

 Hamerton. The technique employed was an adaptation of 

 the Feulgen squash method. The animals were injected with 

 colchicine one hour before sacrifice and the tissues were 

 handled as suspensions. 



The results to date may be summarized as follows. Of the 

 bone marrow cells in metaphase which could be scored, the 

 great majority have been identified by means of the marker 

 as originating from the donor (Table III). This holds also for 



Table III 



Preliminary Data of Ford and Hamerton on Identification of Markers 

 IN Cells at Metaphase (+ Present, — Absent, ? Doubtful) 



* Mostly cells showing classical signs of damage from radiation. 



the much more limited examination of spleen, lymph gland 

 and thymus, the only tissues as yet of which satisfactory 

 preparations have been made. For each time of examination 



