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to use more collodion, only when quite large objects are to be pla- 

 ced. The tendency is generally to leave too much, rather than too 

 little, of the collodion. 



With a spear pointed needle, remove an embryo from the inclined 

 plane, by drawing it over the edge of the linen, fig. 2. As the embryo 

 has a little oil adhering to its surface, it will not be broken by the process, 

 and for the same reason it will adhere to the surface of the needle. 



Embryos that are not exactly spherical will take up a rather de- 

 finite position on the needle. Naturally the largest surface of the em- 

 bryo will be applied to the surface of the needle. In scraping it off 

 the linen, it will roll against the needle until its longest axis is paral- 

 lel to the axis of the needle. An embryo that has three unequal dimen- 

 sions will tend to have its longest axis parallel with the axis of the 



fig. 3. 



fig. 2. 



needle, its shortest axis at right angles to the surface of the needle, 

 and its intermediate axis at right angles to the axis of the needle and 

 parallel to its surface. These positions are, of course, only approximate 

 but by taking them into account, the embryo can be placed on the 

 strip so that it will need to be moved but very little, to put it in the 

 desired position. 



The embryo should lie on the surface of the needle very near one 

 edge, fig. 3. When the surface of the needle becomes oily, the embryo 

 is frequently pulled away from the edge. 

 From this position it cannot be placed on 

 the strip without danger of injuring it. 

 To avoid this difficulty the needle should 

 be occasionally dipped into alcohol or 

 xylol and wiped dry. 



To transfer the embryo from the 

 needle to the strip, keep the surface of 

 the needle perpendicular to the surface 

 of the strip, touch the edge near which 

 the embryo lies, to the prepared surface, 

 fig. 4, and raise it directly away from the 



strip. The embryo, now held by the collodion, will slip off. over the 

 edge of the needle without being dragged out of position. When the 



fig. 4. 



