J, to BIOLOGICAL LABORATORY OF SYDNEY UNIVERSITY, 



2. On some RECENT Histological Methods, and their adapta- 

 tion TO the teaching op practical Histology. 



Some methods, recently described, of dealing with objects 

 intended for histological examination are not only great boons to 

 the original worker, lessening greatly the drudgery of manipula- 

 tions, and enabling him to prepare and examine a large amount of 

 material in a comparatively short time ; but are, in certain 

 instances, of great service also to the teacher of histology, 

 as, when perfected, they will enable him to su})ply the largest 

 class without much loss of time with a uniform series of prepara- 

 tions so preserved and stained as to bring out all the main points 

 in their microscopic structure. A short account of my experience 

 of some of these methods in connection with class work, will 

 perhaps be of service to others who have to do with the teaching 

 of natural science. 



STAINING WITH H^EMATOXYLIN. 



Objects which have been hardened by any of the usual methods, 

 after having been at least a fortnight in alcohol, are best stained 

 en bloc by an aqueous solution of crystallised haomatoxyliu, 

 followed by bichromate of potash as recommended by Heidenhain. 

 (1) Eor most organs and tissues, pieces half an inch square, are 

 most successfully and uniformly stained through by means of a 

 ^ per cent, solution of hsematoxylin allowed to act for 10 to 24 

 hours ; the staining agent is followed by a 1 per cent, solution of 

 bichromate of potash, which should be allowed to act for two or 

 three hours. It is quite impossible, I need hardly add, to lay 

 down any precise rule as to the time required for staining 

 satisfactorily portions of any given organ ; though twenty-four 

 hours immersion in a half-per-cent. solution of hsematoxylin will, 

 in the majority of cases, give satisfactorily results, in some 

 instances the object will be rendered too black, and in others will 

 be found not to be stained throughout. The tissues which require 

 the most prolonged staining, when hardened by one method, may 



(1) Pfliiger's Archiv., XXIV. (1884), p. 468. 



