CINEPHOTOMICROGRAPHY 



83 



CLEARING 



nique to demonstrate that the latero- 

 frontal cilia of Mytilus are compound 

 and that the separate components can 

 beat independently of the others. 

 Peterfi, T., and Woerderman, M. W. 

 (Biol. Zentralbl., 1924, 44, 264-268), 

 Grave, C. and Schmitt, F. O. (J. Morph. 

 and Physiol., 1925, 40, 479-515), Lucas, 

 A. M. (J. Morph. 1931, 51, 147-193) and 

 Worley, L. G. (J. Cell, and Comp. 

 Physiol., 1941, 18, 187-197) employed 

 this method to gain information con- 

 cerning ciliary coordination. 



Cinephotomicrography. A convenient illus- 

 trated account of apparatus and meth- 

 ods is given by Tuttle, H. B., in Glas- 

 ser's Medical Physics, 183-194. See 

 Motion Pictures. 



Cinnamon Oil (Cassia oil) resembles clove 

 oil and is particularly recommended by 

 Lee (p. 70) for clearing. Two kinds are 

 given in Merck Index. The U.S.P.XI 

 variety contains 80-90% cinnamalde- 

 hyde. 



Citrate of sodium can be used as an antico- 

 agulant in the proportion of 18 cc. of 2% 

 aq. sodium citrate to 100 cc. of blood. 



Clarite X (Neville Co., Pittsburg) 60% in 

 toluol is suggested as substitute for 

 balsam owing to its neutral reaction, 

 lack of yellow color and quickness oi 

 hardening. Clarite, also called Nevil- 

 lite V, is useful if added to paraffin when 

 one wishes to obtain thin sections when 

 it is not convenient to imbed in a very 

 high melting point paraffin. Wehrle, 

 W., Stain Techn., 1942, 17, 131-132 ad- 

 vises imbedding in a mixture of 90% 

 paraffin (m.p. 53°C.), 5% bleached bees- 

 wax and 5% clarite and the elimination 

 of electrical charge when ribbons are 

 cut by a spark-coil device described by 

 Blandau, R. J., Stain Techn., 1938, 13, 

 139-141. 



Clark and Lubs Buffers (Clark, W. M. The 

 Determination of Hydrogen Ions, Balti- 

 more: Williams & Wilkins, 1928, 717 

 pp.). Prepare: (1) A solution contain- 

 ing M/5 boric acid and M/5 potassium 

 chloride made by dissolving 12.368 gms. 

 of H3BO3 and 14.912 gms. of KCl in aq. 

 dest., and diluting to 1 liter. (2) A 

 M/5 sodium hydroxide (carbonate free) 

 solution by dissolving 50 gms. of NaOH 

 in 50 ml. (cc). aq. dest. in a Pyrex 

 flask. Let stand overnight to allow the 

 sodium carbonate to settle, or filter 

 through a Gooch or sintered glass cruci- 

 ble. (Exclude air to prevent formation 

 of more carbonate by atmospheric CO2.) 

 Keep the strong alkaline solution in a 

 paraffin-lined glass bottle. Dilute with 

 aq. dest. which has been boiled to re- 

 move the excess CO2 so that the solution 

 is about 1 N. Then make an approxi- 

 mately M/5 solution of the alkali which 



can be accurately standardized against 

 potassium acid phthalate. 



To make buffer of the desired pH add 

 to 50 cc. of (1 ) M/5 HjBC-KCl the desig- 

 nated amount of (2) M/5 NaOH and 

 dilute to 200 cc. with aq. dest. Or 

 combine the two in similar proportions 

 but in larger amounts to minimize error 

 in measurement. 



Cleaning Glassware. Pulverize 20 gms. 

 potassium bichromate. Dissolve this in 

 200 cc. aq. dest. with aid of a little heat. 

 Add slowly 20 cc. sulphuric acid C.P. 

 Before treating beakers, graduates, 

 bottles, etc. with this acid cleaning solu- 

 tion first wash them in soap and hot 

 water. Rinse in water to remove the 

 soap. Leave in cleaning solution 2 hrs. 

 or more. Rinse in running tap water and 

 dry with opening downward on drying 

 racks as in biochemical laboratories if 

 possible in a dust free cupboard. For 

 new slides and cover glasses wash in the 

 same way and after final rinsing in tap 

 water store in fresh 95% alcohol in 

 covered dishes until they are required 

 for use when they should be wiped with 

 gauze. For old slides and cover glasses 

 soak in xylol to permit separation and 

 removal of most of balsam. Then leave 

 in waste alcohol several days. Soak for 

 a day or more in strong soap solution. 

 Wash in running water. Clean in clean- 

 ing solution. Wash in water and store 

 in 95% alcohol. Unless strict economy 

 is necessary it is hardly worthwhile to 

 use slides and covers twice especially 

 when the former have been marked with 

 diamond pencils. 



Clearing is a process in microscopic tech- 

 nique which is required in three different 

 situations. 



1. As the step following dehydration 

 in paraffin imbedding. The tissue be- 

 comes translucent but this is not the 

 essential feature of the process. What 

 is necessary is for the alcohol, which is 

 not a paraffin solvent, to be removed by 

 the clearing agent before the tissue is 

 infiltrated with paraffin. Consequently 

 the agents must mix freely with alcohol 

 on the one hand and with paraffin on the 



