470 SYDNEY J. HIOKSON. 



aud now widely used in England and elsewhere under 

 the name of the " Iron-Hsematoxylin method." This experi- 

 ment did not give results that were at all satisfactory. 

 Another series of experiments which have been made in the 

 Owens College laboratory by Mr. Wadsworth, under my 

 direction^ have shown that the most satisfactory results are 

 obtained by the following method : — " The sections are placed 

 ill a solution of iron-alum (1 per cent, iron-alum in 70 per cent, 

 alcohol) for one to three hours, and then placed, after slight 

 washing in 70 per cent, alcohol, in a A per cent, solution of 

 pure brazilin in 70 per cent, spirit." 



Brazilin stains much more slowly than hsematoxylin, aud 

 we have found that generally it takes several hours (three to 

 sixteen) to give a good sharp definition. After staining, the 

 sections are washed in pure 70 per cent, spirit, passed 

 through the usual stages, and mounted. There is seldom any 

 need to wash the sections in iron-alum after staining. It will 

 thus be seen at the outset that this method possesses two 

 advantages over iron-hgematoxylin, — the sections are never 

 taken down into water, and the number of washings is con- 

 siderably reduced. 



The results are, to my mind, eminently satisfactory ; for 

 not only is brazilin a definite chromatin stain, but in nearly 

 all tissues some parts of the cytoplasm are also stained, 

 though of a different colour. It is in most cases a double 

 stain, but with some tissues it is a treble stain. 



We have used as a test object a series of sections through 

 the body of a larval newt. Each of these sections exhibits so 

 many subjects of histological interest that it is impossible to 

 describe them briefly. I think it would be admitted, however, 

 by all observers that nearly, if not all the tissues are well 

 stained. The chromosomes in the cells that are dividing in 

 the skin and ovary are very sharply defined and of a deep 

 purple colour, while the granules in the cytoplasm are brown. 

 On making a comparison of our preparations of newt's testis 

 stained by the iron-brazilin method and by the iron-haema- 

 toxylin method^ it was found that the karyokinetic figures 



