86 CHAPTER VIII. 



Fbancotte {Ball. Soc. Belg. Mic, 1884, p. 45) produces the retiuisite 

 vacuum by the condensation of steam. 



FoL (Lehrb., p. 121) employs the vacuum apparatus of HofEmaun, Ijut 

 simplifies the arrangement for containing the paraf&n. The paraffin is 

 contained in a stout test-tube furnished with a rubber stopper traversed 

 l)y a tube that puts it into communication with the pump. The lower 

 end of the test-tube dips into a water bath. Ton pump out the air once 

 or twice, wait a few minutes, then turn out the object with the paraffin 

 (which by this time will have become abnormally hard), and re-imbed m 

 fresh paraffin. 



See also Peingle, in Jom-n. Path, and Bacterial., 18!I2, p. 117; or 

 Jourii. Roy. Mic. Soc, 1892, p. 893; Kolsteb, in Zeit. iviss. Mile, xviii, 

 19ffl, p. 170; Bbbg, Zeit. wins. Mile, xxvi, 1909, p. 209; Fuhkmann, 

 ibid, xxi, 1904, p. 402 ; Kolmee and Wolpf, ihid., xix, 1902, p. 148 ; 

 Gbmmill, Joiirn. Soy. Mic. Soc, 1911, p. 26. 



142. Imbedding and Orientation. — A'i soon ((.y tlie objects arc 

 thorouglily saturated with paraffin tliey should he ivihedihd 

 by one of the methods given above (§ 137), and the paraffin 

 cooled as described next §. 



But it may be desirable to have the object fixed in the 

 cooled paraffin in a precisely arranged position^ andj above 

 allj in a precisely mai'ked ])Osition. Very small objects may 

 be oriented as follows : — The object is removed from the 

 melted paraffin, and placed on a cylinder of solid paraffin. 

 A needle or piece of stout iron wire is now heated in the 

 flame of a lamp, and with it a hole is melted in the end of 

 the cylinder ; the specimen is pushed into the melted 

 paraffin, and placed in any desired position. The advan- 

 tages of the method lie in the quickness and certainty with 

 which it can be performed. In using the needle it is 

 important to melt as little parci'ffin as jios.sible at one time, in 

 order that that which is melted may cool again as rapidly 

 as possible. 



Keeb {Quart. Journ. Micr. Sc., xlv, 1901, p. 4) employs 

 an electrically heated needle. 



The method of Patten (Zeit. wins. Mil;., xi, 1894, p. 13) is useful 

 when one desires to orient large numbers of small objects. You get 

 some writing paper of the sort that is made with two sets of raised 

 pai'allel lines running at right angles to each other ("linen cloth paper"). 

 Small strips are cut from this, and at suitable intervals along them small 

 drops of a mixture of collodion and clove oil, of about the consistency of 

 thick honey, are arranged close together along one of the ribs that run 

 lengthwise. The objects to be imbedded are cleared in clove oil or oil of 



