SERIAL SECTIONING. 



It is often very desirable and indeed quite necessary that the 

 whole of an organ be studied systematically, but to do this requires 

 that the parts not only be placed in a condition to be observed, 

 but also, that the arrangement of parts as sectioned be so system- 

 atic as to show the relation of each section to the whole. This 

 can be accomplished by making what are known as serial sections 

 of the object. In this case it is necessary that the sectioning be 

 done in a microtome in order to preserve a uniform thickness. 

 The sections as cut, should be arranged on the slide close to each 

 other and in the same order as they are removed from the object. 

 They should also occupy the same position with reference to the 

 relation of each section to the whole. 



With the paraffine method when "ribbon sections" are cut, it 

 is only necessary to break off pieces of ribbon and lay them along- 

 side of each other in the order in which they are removed. 



With the collodion method as the sections are cut, they should 

 be taken up with a camel's hair brush and transferred to the slide. 

 After being arranged in position, they should be sealed by blowing 

 over them a little ether vapor. The slide should be kept constantly 

 wet with alcohol to prevent the sections from drying or shriveling. 

 The arrangement of sections on the slide should be uniform at all 

 times. A very convenient order is to begin in the upper left hand 

 corner and place the sections under each other in a row along the 

 longest axis of the slide. After the row has reached to within 2 

 c. m. of the opposite end, a new row is begun at the right of the 

 old one, and at the top of the slide; 5x2^ c. m. cover glasses will 

 be required. 



