

HOW ZOOLOGISTS DO THEIR WORK 185, 



men along with it is poured into a little mould 



and left to cool. The block of wax containing 



the specimen is cut down to a quadrangular 



shape, and is now ready for section cutting. In 



old days the block was 



placed in a stand, 



and successive sec- 



tions were cut from it 



by hand with a razor. 



But this process is 



much too slow for 



modern days. Ma- 



chines called micro- 



tomes (/. e. cutters of 



small parts) have been 



invented, and of these 



there are several kinds 



in all, however, the 



razor is worked by 



machine and not by 



hand, so as to secure 



steadiness and a uni- 



form thinness of the 



sections. The old mi- 



crotomes threw off 



each section separate- 



ly; but now matters 



* * 

 ^1 



* 



* 

 % 



FIG. 47. Sections of Embryo 

 Chick, eight days old. A slide 

 mounted for microscopic ex- 

 amination, showing sections 

 arranged in ribbons. 



are so arranged that the wax of each section ad- 

 heres to that of the next, and the whole series of 

 sections forms a continuous ribbon of thin wax. 

 A large specimen, affording a number of sections, 

 thus results in a ribbon of considerable length. 

 Further processes are now required to fit the sec- 

 tions for the microscope. The ribbon must be 

 divided into successive pieces of a length deter- 

 mined by that of the slides to be used. These are 



