14 PROTISTS AND DISEASE 



As Wilson points out, there is no specific stain for 

 chromatin. Similar staining reactions do not necessarily 

 mean chemical identity ; both the nuclei and matrix of 

 cartilage stain alike with methyl green. 



Staining reactions have their value and we should be 

 able to make use of every technical resource ; at the same 

 time we must not forget that a process which reveals one 

 feature brilliantly will conceal others of equal importance ; 

 nor that technique is a means, not an end. 



Bodies suspected of being protists should invariably be 

 first carefully examined unstained in conditions as nearly as 

 possible like those in which they are discovered, and then in 

 water. In this way alone can we let them show by their own 

 activities if they are living organisms. They should also be 

 tested by attempting cultures in water as described below in 

 Chapter VI. 



Intravital Staining. Methylene blue, neutral red, and 

 other dyes are used to stain living tissues and organisms. 

 Their applicability is limited ; it is generally agreed that 

 when a nucleus takes a stain it is dead. Neutral red stains 

 granules, and it has the advantage of being a test of acid or 

 alkaline reaction, becoming brighter red with the former, 

 yellow with the latter. It is a basic dye, its name referring 

 to its tint. Janus green (Hoechst) has been found to stain 

 the mitochondria of living human lymphocytes ; mitochondria, 

 being soluble in alcohol, chloroform, and ether, are destroyed 

 by the ordinary processes. 



