430 SOME OTHER HISTOLOGICAL METHODS. 



washed away, because they have the property of adhering to 

 glass ; and on bringing the slide under the microscope they 

 will be seen in large numbers. If it be desired to make 

 permanent preparations of them, they should first be fixed. 

 This is done by putting a drop of osmic acid solution on the 

 finger before pricking it. 



For BIZZOZEEO'S recent methods for the numeration of these elements 

 and for the study of their regeneration, see his paper in Festschr. R. Vir- 

 chow gewidm.y &c., 1, 1891, p. 459 ; or the report of the methods in Zeit. /. 

 VJ188. Mik., ix, 2, 1892, p. 229. 



For the application of some digestion methods to the study of blood-plates, 

 see LILIENFELD, Arch. f. Anat. u. Physiol., Physiol. Abth., 1892, p. 115 ; 

 or Zeit.f. wiss. Mik., ix, 3, 1893, p. 363. 



806. BIONDI'S Section Method for Blood (Arch. f. mik. 'Anat., xxxi, 

 1888, p. 103). None of the foregoing methods are perfectly satisfactory as 

 regards the preservation of the elements of blood without deformation, and 

 at the same time in a perfectly permanent manner. Biondi's ingenious pro- 

 cess does this. 



Blood is fixed with osmic acid solution as described above, 803. Four 

 or five drops of the mixture of blood and osmium solution are then mixed 

 with agar-agar jelly melted at 35 to 37 C. The whole is allowed to cool, 

 and the mass is put to harden in alcohol of 85 per cent. After a few days 

 the mass will have attained a consistence that allows of its being imbedded 

 in pith and cut with a microtome. The sections are treated according to 

 the usual methods. The best stains are obtained with methyl green, 

 methylen blue, fuchsin, and safranin. Methyl green and eosin is also a 

 good combination. After staining, the sections are cleared and mounted in. 

 balsam in the usual way. 



Thinner sections can be obtained if the agar-agar mass be imbedded in 

 paraffin in the usual way, instead of in pith. 



Instructions, too long to be abstracted here, are given for the preparation 

 of a suitable agar-agar mass. It may be obtained ready prepared from 

 Herrn Konig, 29, Dorotheenstrasse, Berlin. Celloidin, and others of the 

 usual imbedding masses, were tried, but without success. SCHIEFFEE- 

 DECKER, however, says that celloidin may be employed (see his Gewebelehre, 

 p. 389). 



For further details the English reader may consult the Journ. Roy. Mic. 

 Soc., 1888, pp. 313, 659. 



This is undoubtedly a valuable method, and is capable of extension to the 

 study of other animal fluids besides blood. 



Glands. 



807. Mucin. It has already been stated that the blue 

 solutions of hsematoxylin have a special affinity for mucin. 

 For the demonstration of mucus gland-cells the following 

 process is, therefore, recommended by FLEMMING (Zeit. f. 



