734 SUMMAKY OF CURRENT RESEARCHES RELATINQ TO 



allows tlie cavity C to be made larger or smaller ; on the other side the 

 screw F pushes the inclined plane in the direction of the arrow, and 

 elevates the object more or less above the plate G. 



Fig. 151. 



Dr. P. Latteux recommends the instrument more particularly for 

 Lairs. 



Cutting Sections of Hairs.* — Dr. P. Latteux has found that 

 transverse sections of hairs are very difficult to obtain by the methods 

 indicated in text-books, the section not being made at right angles to 

 the direction of the hair, so that instead of being round it is oval. Ho 

 has therefore been driven to devise the following process which enables 

 excellent preparations to be made. 



A small piece of wax is placed at one end of a piece of glass, and 

 the hair which it is desired to cut is fixed in the wax by making a 

 hole for it with a hot needle, A second and a third hair are fixed in 

 the same way by the side of the first. 



A small piece of diachylon plaster of the width of the glass is then 

 applied at the other end. It will readily adhere to the glass on 

 being simply pressed with the finger. A small quantity of wax is 

 then placed on the plaster, and taking the hairs one by one they are 

 fixed by their free ends so that they are all parallel and arranged like 

 the strings of a violin. 



The point now is to fix them in a mediima sufficiently solid to keep 

 them in their place, and so that they may not spring back and become 

 sinuous. For this purpose nothing is so useful as collodion. A layer 

 of this is to be spread between the two points where the wax has been 

 placed, and when the ether has evaporated the hairs will be imbedded 

 in a layer of the substance. It sometimes happens that at this moment 

 the hairs relax. The strip of diachylon plaster is then to be carefully 

 detached and fixed a little further ofi", stretching the hairs gently. 

 Another layer of collodion is then to be poured on and this repeated 



* Latteux, P., ' Manuel de Technique microscopiquc,' 2ad cd., 1883, pp. 263-6. 



