478 



GENETICS OF SOMATIC CELLS 



of fixatives to nutrient medium of tissue cultures after the addition of the hypotonic 

 agent (tap water or hypotonic salt solutions) renders the tissue more favorable both to 

 wet and air-dried squashing procedures. This has been observed independently by 

 several investigators. 



The use of 1.0 N HC1 as a softening agent 1320 is a carryover of the action noted 

 during the Feulgen technique used in plant cytology. It dissolves the calcium pectate 

 that binds meristematic cells and thus leads to better squashing. 239 Ruddle 1084 



Fig. 61. Culture (primary) of skin from 



A MALE HOUSE MOUSE, MuS mUSCuluS. 



Fig. 62. Hypotetraploid ehrlich's 



ASCITES TUMOR. 



» 9 ' <r 



fir » . • 



•I '.** //-^ 



Pretreatment with colchicine and 

 hypotonicity, fixation and staining pro- 

 cedures employed by Makino and Sasaki 842 

 and Awa, Sasaki, and Takayama. 41 (Photo- 

 graph by S. Makino and M. Sasaki.) 

 2600 X. 



Colchicine (25 x lO" 6 M/10 g. body 

 weight) administered intraperitoneally six 

 hours prior to aspiration or removal of 

 tumor, hypotonicity (tap water 50 per cent 

 by volume) for 10 minutes prior to adding 

 3 : 1 fixative (50 per cent by volume) and 

 storing. A drop of fixed cells is added to 

 a drop of aceto carmine on a siliconed slide 

 and squashed, following conventional pro- 

 cedures. 2250 X. (Phase microscopy. 

 Photograph by R. Kato.) 



employs 1 .0 N HC1 as a cytoplasmic clarifying agent for trypsinized, cultured cells of 

 pigs that are directly fixed and stained with aceto-orcein. The cellular membrane 

 becomes more elastic and thereby encourages flattening of the intact cells. The 

 adaptation of the procedures employed by Hsu and his associates has proved most 

 productive in the hands of Clausen and Syverton 206 (figure 58). 



A variety of pretreatment schedules have appeared for ascites-tumor cells from 



