4G BULLETIN OF THE 



and warp of some woven fabric. The surface of the paper is thus di- 

 vided into minute squares, the meshes representing the spaces between 

 the imitated threads of the fabric. If such paper is not to be had, any 

 paper that has a distinct grain will answer, provided the lines of the 

 grain are straight and parallel. 



Cut a rectangular strip of the paper so that the cut edges are parallel 

 and perpendicular to the direction of the grain ([ use strips about 

 5x15 mm.) and ])aste it smooth to a glass slide by means of a solution 

 of gum-arabic. The rougher side of the paper, i. e. the side showing the 

 grain more distinctly, should lie uppermost, or exposed. "When the gum 

 has dried, the exposed surface of the paper is coated with a thin film of 

 the gum-arabic solution, which is best applied with a brush. When 

 this is quite dry, the gummed surface of the paper is coated with 

 a thin layer of collodion. This should be ordinary flexible collodion 

 diluted with three parts of ether, and should be applied with a small 

 brush so as to produce a very thin film. The coating of collodion should 

 not be added until immediately before use, for, if allowed to remain too 

 long, it is liable to crack and fall away. The slip of glass tlius prepared 

 with the strip of paper covered with its two films of gum and collodion 

 is then ready for use. 



The object to be oriented, which has been previously cleared in tur- 

 pentine, is now drained of the superfluous oil by means of bibulous 

 paper, and brought on the point of a needle to the surface of the paper 

 prepared as above, and adjusted under the microscope so that the axes 

 of the object have any desired relation to the lines on the paper. If 

 care be taken to drain off all of the turpentine from the object, it will 

 stick to the surface of the collodion in any position in which it is placed, 

 so that an oblong or ovoid object can be placed either on end, or so that 

 its chief axis will make almost any angle with the plane of the paper. 

 \yhen the object is suitably oriented, the whole slide is exposed under a 

 bell glass for a few seconds to the vapor of ether. This softens the 

 collodion, which upon drying holds the object fast in the desired position. 

 The object is then covered with a drop of turpentine, and the slip of 

 glass with the attached paper is placed in the parafiiu bath. 



To imbed the object in paraffin, the slip of glass bearing the object is 

 removed from the bath, and a mould is built upon it about the paper in 

 the ordinary way, by means of bars of metal arranged in the form of a 

 rectangle, and filled with fluid paraffin. The mould should be as nearly 

 as possible of the same size as the strip of paper, that is to say, tlie sides 

 of the mould should coincide with the edges of the paper. When the 



