97 



-- and consequentl>- the contrast between cells and medium 

 is not always the best possible. Another disadvantage in 

 making photos ot lissiie cells in plasma media is, that 

 the cells arc seldom in the same j)lane and therefore dif- 

 ficult to focus on. 



It is necessary I o have a good deal of experience before 

 good microgrammes of tissue cultures can be obtained, 

 Photomicrogrannnes of living and unstained tissue cells in 

 cultures ai-e i-ather difficull to take. The illustrator at the 

 Rockefeller Institute L. Schmidt has contributed much to 

 this particular technique. By special illumination from above 

 the specimen, beautiful photos of living tissue cells have 

 been taken ])y Schmidt. 



The technique of m i c r o-c i n e m a t o g r a p h y has been 

 applied rather much to tissue cells in vitro. The master in 

 that field being Comandoni^i; u2\ \iso Braus^o has 

 been doing that kind of work with great success. 



PREPARATION OF TISSUE CULTURES FOR 

 MICROSCOPICAL PURPOSES. 



The living, unstained culture is a good subject for mici'o- 

 scopic examination, although not everything can be seen, 

 nevertheless high magnification can easily be applied to the 

 tissue cells within the culture chamber. It is advisable to 

 have a microscope with a heating device so that cultures 

 and single cells within the cultures can be followed for a 

 long period of time without allowing the culture to cool off. 



We will now describe some of the simplest and most 

 suitable fixing and staining methods for the nistological 

 investigation. All the many special staining methods can, 

 of course, be applied with some modification of the tech- 

 nique, but they will be disregarded here. Several beau- 

 tiful methods of preparing the tissue cultures are described 

 in the "Praktikum" by R h. Erdmann. In the cultures we 



7 



