1 882.] in the Zoological Station in Naples. 781 



ing by an admixture of lard, as generally done, it is better to use 

 a paraffine which becomes soft in summer, on account of its con- 

 taining liquid hydrocarbons. 



Preparatory to imbedding, the objects are removed from abso- 

 lute alcohol 1 to creosote, clove oil or chloroform, and left until 

 they become thoroughly saturated. The penetration of the clar- 

 ifying fluid may, in some cases, be advantageously hastened by 

 warming a little. They are next placed in soft paraffine, heated 

 to about 50 C. over a water bath, and allowed to remain for an 

 hour or so. The soft paraffine is then turned off and replaced by 

 a mixture of hard and soft paraffine, 2 heated to about 50 C. 

 After remaining for half an hour or less in the harder paraffine, 

 kept at a steady temperature, they are ready for imbedding. For 

 this purpose a small paper box may be used ; or, much better, a 

 box made of two pieces of type-metal, as used in Professor 

 - 1 Leuckart's laboratory. As will be seen 



from the accompanying diagram, each 

 form of a carpenter's 

 ^71 square, with the end of the shorter arm 

 triangularly enlarged outward. A conve- 

 H nient size will be found in pieces measuring 

 7 (long arm) by 3"" (short arm), and / lnm 

 high. With such pieces a box may be 





placir 



ig them 1 



together 



on a round plate of 



1 1 



glass, 



which h 



as previo 



iusly been wet with 





glyce 

 of th< 





gently 

 ill evide] 







- box w 



atly vary according 



'J 



to the 



! position 



given to the pieces, but the 





heigh 



t can be 



varied 



nly by using differ- 



ent sets of pieces. 



[n such 



a box the paraffine may be kept in a 



liquid state by wan 



ning nc 



>w and 1 



:hen ove 



r a spirit lamp, and 



small objects be placed in any desirei 



i positio 



n under the micro- 



scope. 











It is well to imbec 



I in a tli 



iin layer 



of paraffine, so that the ob- 



ject, after cooling, m; 





it out in 



small cu 



bical blocks, which 



