Penetration of methyleneblue into living cells 



after desiccation. 



Proceedings of the Section of Sciences, Kon. Akademie van Wetenschappen, Amsterdam, 

 Vol. XV, 1913, p. 10861088. Verscheen onder den titel Over het indringen van 

 methyleenblauw in levende cellen na indroging in Verslagen Kon. Akademie van Weten- 

 schappen, Wis-en Natuurk. Afd., Amsterdam, Deel XXI, 1913, biz. 930933- 



It is generally known that methyleneblue does not enter living yeastcells, when 

 these are first soaked with water or swimming in a fermenting liquid, whilst it 

 colours the dead cells intensely. It is even possible several days to cultivate yeast in 

 wort, coloured dark blue with this pigment, without the cells being coloured in the 

 least. On wortagar plates with methyleneblue, colourless colonies will develop. On 

 these facts a method is based to ascertain in living yeast the number of dead cells, 

 which gives very good results. 



Meanwhile there is an exception to the rule that the cells, colouring blue are 

 dead, and this exception will be more closely considered here. 



At the examination of dried yeast, most cells of which take a dark blue colour 

 with methyleneblue, whilst only a very small percentage remain colourless, the fer- 

 menting power often proves so great, that no other explanation can be given, but 

 that the blue-colouring cells have for the greater part preserved that power. This is 

 not unexpected, for it is well known that the alcoholic function is more permanent 

 in dicing cells than the power of growth. Meanwhile, counting-experiments, whereby 

 on one hand the number of cells colouring with methyleneblue was microscopically 

 determined, on the other hand by plate culture, that of the cells growing out to co- 

 lonies, showed that from certain dry yeast samples a much greater percentage of 

 colonies developed, than the percentage of cells not colouring with methyleneblue. 

 This fact was indeed unexpected and induced to a more minute observation. 



First of all it was proved that the number of cells, colouring in a dilute solution 

 of methyeneblue, depends on the way in which the solution is brought into contact 

 with the cells. If this is done by introducing dry yeast into the solution, all the 

 cells colour darkblue and cannot be distinguished from the dead ones. In plate cul- 

 tures, however, a greater or smaller number of colonies may be obtained from these 

 cells, although all seem perfectly alike in their dark blue colour, and should be 

 considered as dead by anyone ignorant of their origin. In favourable circumstances 

 the number of colonies mounts even to 100%, which is to say, that all the cells may 

 colour blue and still grow out to colonies. 



This is in particular obvious when the cells are beforehand coloured with methyleneblue, 

 and the coloured material is used for sowing; it is easy then to recognise the blue 



