648 Caldwell's automatic microtome. 



Caldwell's Automatic Microtome. 



With Plate XLII. 



This machine has been devised to save labour to the histo- 

 logist by cutting a very great number of sections suitable for 

 microscopic investigation in a very short time. The machine 

 is worked by hand, and may easily be made to deliver in one 

 continuous band accurately cut sections at the rate of 100 per 

 minute. Much higher numbers than this are obtained in the 

 Cambridge laboratory, where during the past year one raaehine 

 has done all the work for a large class of students. Not only 

 are all the sections of equal thickness, but they are arranged 

 in consecutive order and are all the same side upwards, which 

 avoids a great loss of time and risk of fracture in the mounting. 

 To use it, however, to the best advantage, it is well to drive it 

 by means of some motor, the flywheel being already provided 

 with a groove for the reception of the cord coming from the 

 motor. Where there is sufficient pressure and supply of water, 

 a simple form of water motor seems the most appropriate and 

 least expensive. 



Method of Using the Microtome. 



Place one of the cylindrical vessels supplied with the machine 

 upon a piece of paper on a glass plate, and pour into it suffi- 

 cient melted paraffin to fill it. As this cools the paraffin will 

 contract and will leave a hole, which must be filled ujj with 

 more melted paraffin! 



Melt a small quantity, say an ounce, of embedding material 

 in some suitable vessel ; a small copper pan or a porcelain 



