CHAPTER VIII. 89 



the cork of which passes a small camel-hair brush, which just dips 

 into the collodion with its tip. The collodion should be of such a 

 consistency that when applied in a thin layer to a surface of paraffin 

 it dries in two or three seconds without leaving a shiny surface. It 

 must be diluted with ether as soon as it begins to show signs of doing 

 so. 



Take the brush out of the collodion, wipe it against the neck of 

 the bottle, so as to have it merely moist with collodion, and quickly 

 pass it over the free surface of the preparation. Care must be taken 

 not to let the collodion touch the vertical surfaces of the paraffin, 

 especially not the one w r hich is turned towards the operator, as that 

 will probably cause the section to become stuck to the edge or under- 

 surface of the knife. As soon as the collodion is dry, which ought 

 to be in two or three seconds, cut the section, withdraw the knife, 

 and pass the collodion brush over the newly exposed surface of the 

 paraffin. Whilst this last layer of collodion is drying, take up the 

 section from the knife and place it with the collodionised surface 

 downwards on a slide prepared with fixative of Schaellibaum. Then 

 cut the second section, and repeat the manipulations just described 

 in the same order." 



HENKING (Zeit. wiss. Mik., iii, 1886, p. 478) takes instead of collodion 

 a solution of paraffin in absolute alcohol. 



For extremely brittle objects, such as ova of Phalangida, he recom- 

 mends a thin (light yellow) solution of shellac in absolute alcohol. 



HEIDER (Embryonalentw. v. Hydrophiliis, 1889, p. 12 ; cf. Zeit. wiss. 

 Mik., viii, 1892, p. 509) employs a solution made by mixing a solution of 

 gum mastic in ether, of a syrupy consistency, with an equal volume of 

 collodion, and diluting the mixture with ether until quite thin and 

 liquid. 



KABL (ibid., xi, 2, 1894, p. 170) employs superheated paraffin (of about 

 100 C.). This has the advantage of filling up any cavities there may be 

 in the objects, and also of preventing the sections from rolling. A compli- 

 cated development of this process is described by LENDENFELD in Zeit. 

 wiss. Mik., xviii, 1901, p. 18. 



APATHY (Mikrotechnik, p. 183) employs a 1 per cent, solution of 

 celloidin, allows the sections to roll, and unrolls them by the water- 

 process ( 149). 



JORDAN (Zeit. wiss. Mik.) adds 5 drops of oil of cedar to 15 c.c. of the 

 solution of celloidin, and finds that rolling is prevented. 



148. Ribbon Section-cutting. If a series of paraffin sections be 

 cut in succession and not removed from the knife one by one as cut, 

 but allowed to lie undisturbed on the blade, it not unfrequently 

 happens that they adhere to one another by the edges so as to form 

 a chain or ribbon which may be taken up and transferred to a slide 



