10 Biological Stains 



those early days. The fact that the microscope is now being used 

 successfully in the hands of so many students who would not think 

 of comparing themselves with the pioneers in microscopy is due 

 to the use of stains more than to any other factor — although, of 

 course, no one can deny that modern improvements in the micro- 

 scope have also played a part of great importance. 



As a matter of fact, a revolution of a different sort, which has no 

 relation to staining, is in progress at the present time. The last 

 few years have brought out more radical changes in microscope 

 design — including that of the electron microscope — than have been 

 seen for the greater part of a century. What will be the outcome 

 of such radical departures as the use of electron beams, X-rays, 

 phase differences, reflecting optics, is still impossible to predict. 

 One might almost assume that the use of improved types of micro- 

 scopes would eventually eliminate the need of stains to render 

 objects more easily visible — were it not for the equally rapid de- 

 velopment in histochemistry, in which field dyes or similar reagents 

 are apt to be needed for a long time to come. 



The present is hardly the place to go into the history of staining 

 in any detail; it has been adequately treated elsewhere. Gierke 

 (1884) w^as the first to discuss the subject, and presented a fairly de- 

 tailed account of the early uses of biological stains, as they were 

 understood at that time in Germany, and brought the subject up 

 to the date on w^hich he wrote. Conn (1933, 1948) has presented a 

 rather more cursory review on staining history, up to modern 

 times, based on a study of moderately recent publications without 

 making any search through old texts. Such a search has been 

 made recently, however, by Lewis (1942) who has presented the 

 most thorough review of the beginnings of staining that has yet 

 appeared, and shows that its origin can be traced way back to 

 Leeuwenhoek, the ''father of the microscope", and the first scien- 

 tist to see bacteria. 



Histological technic, as we know it today, seems to have become 

 fairly well understood about 1860, and it embraced the use of cer- 

 tain natural dyes, notably carmine, but also indigo, madder, 

 saffron and phytolacca. This rapid development of the subject 

 followed a paper by Gerlach (1858) in which he particularly called 

 attention to importance of staining (with carmine) in histology. 

 It is not certain whether or not Gerlach thought he had originated 

 the idea; but it is clear that he was hailed as the father of staining 

 by many of his contemporaries, particularly in Germany. Care- 

 ful students of the subject, however, like Gierke, took pains to ex- 

 plain that though Gerlach had established (eingefurt) staining 

 technic, the actual use of dyes in microscopic work preceded him. 

 Gierke cites Goppert and Cohn (1849) as the earliest users of bio- 

 logical stains. Subsequently, however, the introduction of stains 

 into microscopic work has been ascribed to Ehrenberg (1838); 



