PROTOZOA 11 



be triangular in shape, and the two cover-glasses should be cemented 

 to the slide with fish-glue. The specimens for embedding should be 

 prepared in a watch-glass as far as the xylol stage, and then conveyed 

 by means of a pipette into the micro-aquarium. The latter should be 

 maintained in an upright position, and the organisms will be found 

 to collect in the apex of the triangle. The xylol is now replaced by 

 paraffin, and as soon as the objects have become saturated the glass 

 slide is put into cold water. This hardens the paraffin and, at the 

 same time, dissolves the fish-glue which keeps the cover-glasses in place, 

 leaving free the triangular block of paraffin with the Protozoa clustering 

 at its apex. 



Schaudinn's method should be employed whenever it is desired to 

 arrange single Protozoa (Infusoria, Gregarines) in such a, way that 

 a series of sections may be cut from them. But in order to do this, 

 a material must be added to the xylol which will keep the single 

 Protozoa in place and allow of their being controlled by the micro- 

 scope. For this purpose, Schaudinn recommends the woolly palea of 

 the young fronds and stems of the Java tree-fern, Cibotium cummingii, 

 which is sold by druggists under the name of Penghawar-Djambie. 

 It is an extremely fine-fibred felty substance, which may be easily cut 

 when embedded in paraffin. After it is put into the micro-acquarium, 

 a small groove is made in it with a blunt wooden point, and into this 

 groove the object to be embedded is introduced. 1 



The best methods of staining are by the ordinary haematoxylin, 

 Heidenhain's iron-haematoxylin, the Komanowsky stain, and the 

 colouring of the living organism with neutral red. 



Haematoxylin is the most valuable agent for staining the nuclei of 

 Protozoa. The best form is undoubtedly Mayer's haemalum, although 

 the older alum-hsematoxylin preparations may be used, the most con- 

 venient being Delafield's formula. The stain should be well diluted 

 with distilled water or 1 per cent, alum solution, and cover-slip pre- 

 parations and sections should be allowed to remain in soak for several 

 hours ; they may even be put in over night. They should be washed 

 in running water and then examined under the microscope. If suffi- 

 ciently stained, the specimens are then rinsed successively in 50 per 

 cent., 70 per cent., 90 per cent., absolute alcohol in xylol, and after- 

 wards mounted in Canada balsam, or in cedar wood oil which has been 

 thickened to the consistency commonly used with an oil immersion 

 lens. Canada balsam should be dissolved in xylol, and, when working 

 with haematoxylin, it is expedient to use only those preparations 



1 In their " Grundziige der microscopischen Technik," 3rd Ed., p. 91, Lee and 

 Mayer give a number of methods for placing small objects when embedding in 

 paraffin. These are, however, somewhat more complicated than the method 

 described above. 



