154 Invertebrate Zoology. 



The Paraffin Method. The object, which should be 

 of small size, not often exceeding i cu. cm., having been 

 stained, is thoroughly dehydrated as previously directed. 



From absolute alcohol the object is to be placed in some 

 fluid that will mix on the one hand with alcohol and on 

 the other with paraffin. Such fluids are oil of cedar, oil of 

 clove, oil of creosote, turpentine, chloroform, etc. Immer- 

 sion for two hours in any one of these will often be sufficient. 



Flakes of paraffin are now whittled into the oil, or chloro- 

 form, until the point of saturation is reached, and the speci- 

 men allowed to stand for an hour or longer. If the fluid is 

 warm, a less time may suffice. 



The object is now taken from the saturated oil or chlo- 

 roform, and placed in melted paraffin, the temperature of 

 which should not exceed 35 C. In from one to two hours' 

 time the object will be thoroughly infiltrated. 



Make now a paper box, somewhat larger than the object, 

 and by means of a warm pipette fill the box with paraffin, 

 and place the object therein, noting the position in which it 

 lies. 



In a few moments a film will have formed on the surface 

 of the paraffin, when the box may be placed in a glass of 

 water until thoroughly cold. 



Remove the box, wipe dry, and with a sharp knife trim 

 off the paper from around the block of paraffin. Bearing in 

 mind the position of the object when dropped into the box, 

 scratch on the block a line that will designate the plane in 

 which the object is to be sectionized. 



If the object is not to be immediately cut, it should be 

 properly labelled and placed away for safe-keeping. 



