156 



W. Krause, 



lutions do not stain deeply enough, though specimens stained by them 

 bear high powers well. The blue solutions leave the protoplasm of 

 the cells almost uncoloured; and the dark colour of the nuclei, and 

 of the lymphoid cells, prevents the other features of the specimen 

 from being well seen, in fact such specimens are very unsatisfactory. 



The difference in colour of the haematoxylin solutions depends 

 almost entirely on the alum which is used in making them. It is 

 true that the different woods give a slightly different extract, but the 

 variation between the extracts, whether they are made from Cam- 

 peachy or Jamaica, Honduras or St. Domingo woods, is so slight as 

 not to be of any real importance. The alum by keeping becomes 

 more acid, and acid, as is well known to chemists, turns the blue 

 colour of haematoxylin, red. The most intensely blue colour is ob- 

 tained by using freshly -prepared dried alum, while old powdered 

 crystals of alum (potash alum) give a most decided red or even a 

 yellow colour. The proportion of alum to the haematoxylin extract 

 is also somewhat important. If the proportion sinks below three of 

 alum to one of extract, the red colour will probably be seen ; but, in 

 that case, the staining properties will not be so good. Any amount 

 of alum, above three of alum to one of extract, appears to make little 

 difference to the colour. 



4. Eosin. 



Martinotti *) empfiehlt zu Doppelfärbungen mit Hematoxylin und 

 Eosin, das in Alkohol, nicht in Wasser löslich ist; die Eosinlösung 

 von schön rosafarbener Concentration. Die Auseinandersetzung lautet : 



„Io ho dunque pensato di mettere in pratica un altro metodo 

 che adopero da parecchio tempo, che è assai più comodo e spiccio, 

 che dà risultati eguali e, mi pare, migliori, e che quindi credo di 

 poter raccomandare. Io colorisco le sezioni coli' ematossilina, se- 

 guendo i metodi usuali e poscia le disidrato completamente nell'alcool 

 assoluto. In questo, come si sa, le sezioni colorite coll'ematossilina 

 possono essere conservate per qualche tempo senza inconveniente al- 



*) Sulla colorazione doppia coli' ematossilina e coli' eosina. Estratto dalla Ga- 

 zetta delle cliniche, 1883. N. 51. p. 6. 



