CYTOGENETIC ANALYSIS 



483 



rapidly with tap water and the dishes turned down to drain. Staining is easily done 

 by bathing the clones with a 1 per cent (hematoxylin, toluidine blue, or neutral red) for 

 5-10 minutes, or more, if it is found desirable (figure 66). The stain is retained for 



Fig. 65. Schematic idiogram of the chinese-hamster karyotype. 

 (colchicine pretreatment) 



||||n»»!!NH il 



MALE 



Note X 1 X 2 ; A^F or triheterosomic scheme for somatic sex expression. 



future use by refiltering, and the dish is rinsed several times with tap water and again 

 turned to dry. Visualization of stained clones is inexpensively and most effectively 

 accomplished with the aid of a Bausch and Lomb slide projector placed in a darkened 

 room. Abortive clones, that is, those having 50 cells or less, can be distinguished with 

 great assurance only when viewed with such an instrument. Abortive clones are 

 generally deemed to be negative when determining cloning efficiencies. 



