COLLODION AND OI'HER IMBEDDING METHODS. 105 



Myers (Arch. Anat. Phys., Anat. Abth., 1902, p. 370) 

 takes U per cent., 6 per cent., and 16 per cent. 



See also Neumatee, Zeit. wiss. Mih., xxv, 1908, p. 38 ; De Vecchi, 

 ibid., xxiii, 1906, p. 312 ; and Fuhrmann, Zeit. wiss. Zool., Ixxviii, 1905, 

 p. 524. 



Pish (Journ. Appl. Microscop., ii, 1899, p. 323) first infiltrates with 

 acetone (which he says may be used as a fixing and dehydi-ating agent 

 at the same time), then with a 4 per cent, solution of pyroxylin (gun- 

 cotton) in acetone ; and, lastly, in an 8 per cent, acetone solution of the 

 same. See for other solutions §§ 170 and 171. 



The objects ought to remain in the first bath until very 

 thoroughly penetrated ; — days, even for small objects, — 

 weeks or months for large ones (human embryos of from 

 six to twelve weeks, for instance). 



When the object is duly penetrated by the thin solution, 

 or solutions, if more than one have been employed, it should 

 be brought into the thickest one. This may be done (as first 

 described in this work, 1st edit., 188-5, p. 194) by allowing 

 the thin solution to concentrate slowly (the stopper of the 

 containing vessel being raised, for instance, by means of a 

 piece of paper placed under it), and making up the loss from 

 evaporation with thick solution. 



Apathy {Mikrotechnih, p. 121) holds that it is preferable 

 to transfer to fresh thick solution, as he finds that a better 

 consistencj' after hardening is thus obtained. 



160. Imbedding, — The objects must now, if it has not been 

 done before, be imbedded — that is, arranged in position in 

 the thick collodion in the receptacle in which they are to 

 be hardened. For the usual manipulations see § 137. If 

 paper thimbles be taken for imbedding, the bottoms should 

 be made of soft wood in preference to cork, see § 165. 

 They should be prepared for the reception of the object by 

 pouring' into them a drop of collodion, which is allowed to 

 dry. The object of this is to prevent bubbles coming up 

 through the wood or cork and lodging in the mass. 

 Watch-glasses, deep porcelain water-colour moulds, and the 

 like, also make convenient imbedding receptacles. Care 

 should be taken to have them perfectly dry. 



It not infrequently happens that during these manipula- 



