STAINS AND STAINING 
43 
three alcohols, 50, 95 and 100 per cent, and the first two may be 
simply poured over the slide; in this case, only one Stender dish— 
for the 100 per cent alcohol—is necessary in the alcohol series, the 
other two alcohols being kept in bottles. This short method gained 
great popularity because it was used in Strasburger’s laboratory at 
Bonn. It was the influence of this school and its great master 
which led to the adoption of the short schedule in the second edition 
of this book. A few years’ trial showed the weakness of the method, 
and we returned to the longer schedule. The crudeness of the 
short schedule is doubtless responsible for the tenacity with which 
the Bonn school has clung to the theory of linin and chromomeres. 
The young investigator should be warned that during the last twenty 
years of his life, Strasburger, who had been a leader in technic, cut 
very few sections and did practically no staining, but used prepara¬ 
tions made by assistants. 
Let us now consider a few of the most important stains. 
THE HAEMATOXYLINS 
The most important haematoxylins are Haidenhain’s iron-alum 
haematoxylin, Delafield’s haematoxylin, Mayer’s haem-alum, and 
Boehmer’s haematoxylip. 
All the haematoxylins mentioned contain alum, and, according 
to Mayer, who has written the most important work on haematoxylin 
stains, 1 “the active agent in them is a compound of haematin with 
alumina. This salt is precipitated in the tissues, chiefly in the nuclei, 
by organic and inorganic salts there present (e.g., by the phosphates), 
and perhaps also by other organic bodies belonging to the tissues.” 
These salts are fixed in the tissues by the killing and fixing agent, 
and when the stain is applied a chemical combination results. 
Haematoxylins stain well after any of the fixing agents described in 
1 “Ueber das Farben mit Hamatoxylin,” Mittheilungen aus der Zoologischen Station zu Neapel, 
io:170-186, 1891, and “Ueber Hamatoxylin, Carmin und verwandte Materien,” Zeitschrift fiir 
mssenschaftliche Mikroscopie, 16:196-220, 1899. 
