BY R. VON LENDENFELD, PH.D. 29 



specimen is slowly exchanged for chloroform and, finally, when 

 nearly all the ether is replaced, the specimen sinks down to the 

 bottom. It can then be removed and placed in fresh pure chloro 

 form and left there for 12 hours. 

 It is iiow ready for imbedding. 



The Imbedding in Paraffin. 



The imbedding is also a process which requires much care, 

 patience and experience. If the beginner often loses his specimen 

 in consequence of the want of the latter, he need not be disheart- 

 ened or ashamed ; this happens repeatedly to every one, and I 

 have seen even men like Lang and F. E. Schulze spoil their 

 specimens in imbedding. 



I have found it advantageous to place the specimen for a day or 

 two in molten soft paraffin and keep the latter liquid and at the 

 uniform temperature of 47 — 49° <\, in a self-regulating water-bath 

 stove. During this time all the chloroform has escaped and the 

 specimen can be placed in another little cup with molten hard 

 paraffin kept at a temperature not exceeding 58° C. Pretty 

 hard paraffin will melt at that point. It can be left there for an 

 hour or so and can then be imbedded. A trough of paper or brass 

 measuring 1^ x -i x ^ inches is tilled with molten hard paraffin and 

 at the time when it commences to solidify the specimen is placed in 

 it. The " freezing " surface is kept open by heated needles and 

 the specimen is put in position by the same implements 



It is of the greatest importance to put the specimen in such a 

 position that the desired direction of the sections can be obtained 

 by cutting the paraffin stick, cast in the trough straight across 

 that is vertical to its longitudinal axis. This is often a matter of 

 great difficulty, and it will always be of advantage to throw a 

 ray of reflected and concentrated- sunlight into the molten 

 paraffin, so as to illuminate the specimen properly. It is of 

 course most convenient to cut to an elongate shape before in such 

 a manner that one can tell the position in which it ought to be 

 imbedded by the outer shape of the specimen. 



