SECTIONING PARAFFINE AT A TEMPERATURE OF 



25 FAHRENHEIT. 



KATHARINE FOOT AND E. C. STROBELL. 



/ 



It is with some hesitation that we publish our troublesome 

 device for cutting thin sections of the egg of Allolobopliora, for 

 in other material investigators are able to obtain thin sections 

 without recourse to such complicated methods. 



Our method is quite opposed to established rules, for the 

 best authorities on technique recommend sectioning in a tem- 

 perature varying, according to the season, from 60 to 70 

 Fahrenheit, in some cases employing heat reflected from a lamp, 

 and they advise the use of paraffine having a melting point not 

 higher than 45 to 50 C., emphasizing the fact that harder par- 

 affine is " most hurtful to tissue." 



\Ye found it necessary, however, to use paraffine of a much 

 higher melting point, working slowly toward the use of this harder 

 paraffine, and comparing the results step by step, in order to 

 demonstrate whether the hard paraffine was really harmful to the 

 egg structures. As no injury to the cytoplasmic or nuclear struc- 

 tures could be detected, we finally imbedded the eggs in the 

 hardest paraffine obtainable, that having the melting point reg- 

 istered at 74 C. With this paraffine, a Thoma microtome, and 

 the knife in the best possible condition, we were able to get mod- 

 erately good sections of 5 and 6 ;j., but an attempt to cut thinner 

 sections crushed the paraffine enough to destroy the spherical 

 form of the egg. What was gained by the thinner sections being 

 more than sacrificed by the distortion of nearly all the constitu- 

 ents of the egg. 



We tried to increase the hardness of the paraffine by devising 

 an object carrier that would hold a piece of ice or iced water, but 

 there was little gained by this method. The paraffine could be 

 safely cooled only to a very limited degree below the temperature 

 of the room, beyond this, moisture formed on the block and 



1 Bolles Lee, " The Microtomist's Vade-Mecum." 1896. 



281 



