3. C O N S T R U C T I O N A N D USE OF S Y N T H E T I C M E D I A
109
tive principle, the amounts of salts and vitamins being based on those
found in biological fluids, and the amounts and proportions of amino
acids were those (with some supplements) capable of maintaining
intact animals in nitrogen equilibrium. Only sugar was included in
markedly "non-physiological" concentration, on the grounds that an
empirical increase in the dextrose: NaCl ratio improved survival.
Morgan, Morton and Parker (1950) also took advantage of the growing knowledge and better characterization of a range of vitamins and
amino acids. Even then, however, pure laevorotatory amino acids were
rarely obtainable commercially, and most of the media of this time
contained at least some DL-forms. There has been steady experimentation and development in the Toronto laboratory from the original
medium 199, in a series designated 612, 635, 703, 858, 866 and C M R L
1066 (cf. Parker, 1961). Medium M l 5 0 (Morgan, Campbell and Morton, 1955), a modification of medium 199 containing Hanks' instead
of Earle's salt solution, has been used for many biochemical studies,
mainly on freshly explanted tissues of the embryonic chick, by Morgan
and his co-workers (Morgan, Morton, Campbell and Guerin, 1956;
Morgan and McCrone, 1957; Morgan and Morton, 1957a,b, 1960;
Morgan, Morton and Pasieka, 1958; Morton and Morgan, 1959, 1960,
1961; Morton, Pasieka and Morgan, 1956; Pasieka and Morgan, 1959;
Pasieka, Morton and Morgan, 1956, 1958a,b).
The solutions described in 1955 (Waymouth, 1955) for chick and
mouse cells were devised as modifications of Wilson, Jackson and Brues'
(1942) modification of Baker's (1933, 1936) media. The most significant
points in these designs were the replacement of peptone by a mixture
of amino acids, after the manner of Fischer, and the inclusion of more
of the known vitamins, as White and others had done. The idea behind
these media, in contrast to the comprehensive principle of Morgan,
Morton and Parker, and of White, who included many nutrients
believed but not proven to be useful, was to try to formulate effective
media of as simple composition as possible. The simple media of this
period were, however, not completely adequate for continuous propagation, and recourse was had to supplementation first with both
peptone (Witte's or Difco Bactopeptone) and protein (serum albumin,
Fraction V ) , and then, as the synthetic part was improved, with
peptone alone (Waymouth, 1956). Attempts to fractionate the peptone
led to the conclusion that the active components were principally basic
amino acids or small peptides, and some of the B vitamins. Supplementation with extra histidine and lysine, with vitamin B 1 2 , and with
increased amounts of some of the other B vitamins, resulted in a type
of medium capable of supporting continuous proliferation of mouse
cells ( N C T C 929, Strain L) (Waymouth, 1959).
109
tive principle, the amounts of salts and vitamins being based on those
found in biological fluids, and the amounts and proportions of amino
acids were those (with some supplements) capable of maintaining
intact animals in nitrogen equilibrium. Only sugar was included in
markedly "non-physiological" concentration, on the grounds that an
empirical increase in the dextrose: NaCl ratio improved survival.
Morgan, Morton and Parker (1950) also took advantage of the growing knowledge and better characterization of a range of vitamins and
amino acids. Even then, however, pure laevorotatory amino acids were
rarely obtainable commercially, and most of the media of this time
contained at least some DL-forms. There has been steady experimentation and development in the Toronto laboratory from the original
medium 199, in a series designated 612, 635, 703, 858, 866 and C M R L
1066 (cf. Parker, 1961). Medium M l 5 0 (Morgan, Campbell and Morton, 1955), a modification of medium 199 containing Hanks' instead
of Earle's salt solution, has been used for many biochemical studies,
mainly on freshly explanted tissues of the embryonic chick, by Morgan
and his co-workers (Morgan, Morton, Campbell and Guerin, 1956;
Morgan and McCrone, 1957; Morgan and Morton, 1957a,b, 1960;
Morgan, Morton and Pasieka, 1958; Morton and Morgan, 1959, 1960,
1961; Morton, Pasieka and Morgan, 1956; Pasieka and Morgan, 1959;
Pasieka, Morton and Morgan, 1956, 1958a,b).
The solutions described in 1955 (Waymouth, 1955) for chick and
mouse cells were devised as modifications of Wilson, Jackson and Brues'
(1942) modification of Baker's (1933, 1936) media. The most significant
points in these designs were the replacement of peptone by a mixture
of amino acids, after the manner of Fischer, and the inclusion of more
of the known vitamins, as White and others had done. The idea behind
these media, in contrast to the comprehensive principle of Morgan,
Morton and Parker, and of White, who included many nutrients
believed but not proven to be useful, was to try to formulate effective
media of as simple composition as possible. The simple media of this
period were, however, not completely adequate for continuous propagation, and recourse was had to supplementation first with both
peptone (Witte's or Difco Bactopeptone) and protein (serum albumin,
Fraction V ) , and then, as the synthetic part was improved, with
peptone alone (Waymouth, 1956). Attempts to fractionate the peptone
led to the conclusion that the active components were principally basic
amino acids or small peptides, and some of the B vitamins. Supplementation with extra histidine and lysine, with vitamin B 1 2 , and with
increased amounts of some of the other B vitamins, resulted in a type
of medium capable of supporting continuous proliferation of mouse
cells ( N C T C 929, Strain L) (Waymouth, 1959).