CHAPTER XXXVII. 555 



for in vitro cultures are, 70 per cent, alcohol and 5 per cent, acetic, 

 Flemming, and Bouin. In all cases the cultures on the slip should 

 be first detached from the slide and placed in warm Ringer's solu- 

 tion 37 C. for five minutes. They are then placed in the fixative. 

 Alcohol-acetic gives the cleanest pictures. Staining is best done 

 by Ehrlich's heematoxylin, Delafield's hsematoxylin, iron hsema- 

 toxylin, carmine or Giemsa. As counterstain either eosin or 

 orange Gr. may be used. 



1045. Artificial Culture Media. MARGARET R. LEWIS and W. H. LEWIS 

 (Anat. Record, v, 1911, p. 277) have investigated tissue cultures of chick 

 embryo cells made in artificial media. Eighty combinations of NaCl, 

 CaCl 2 , KC1 and NaHC0 3 and water, to form culture media have been 

 proposed. It was possible to obtain growth in such media, in which 

 either the CaCl 2 or the KC1 or the NaHC0 3 was omitted, but not when 

 the NaCl was left out. Such growths continue only for several days, 

 and are never as extensive as those grown in plasma media. 



More recently MARGARET R. LEWIS (Gontrib. to Embryology, ix, 

 1920, Nos. 27-46) for tissues of chick embryos of four to twelve days' 

 incubation uses " Locke-Lewis " solution (90 c.c. of NaCl 0-9 per 

 cent. + KC1 0-042 per cent., + CaCl 2 0-025 per cent., + NaHC0 3 0-02 

 per cent., + 10 c.c. of chicken bouillon -f 0-25 per cent, dextrose). 

 The embryo was removed from the egg and placed in a petri dish con- 

 taining 20 c.c. of the warmed solution. Pieces of tissue to be explanted 

 were removed, washed through one or more changes of warm medium, 

 and cut with sharp scissors into pieces about 0-5 mm. in diameter ; 

 each piece was then placed in the centre of a coverslip, part of the drop 

 drawn off, and the coverslip sealed on to a vaseline ring around the 

 well of a hollow slide. Cultures thus prepared were kept in an incu- 

 bator at 39 C., and observations made in a warm box at 39 C. 



