1 882.] in the Zoological Station in Naples. 783 



affine itself, is an operation which may, in many cases, be readily 

 accomplished by employing any one of the ordinary intermedia, 

 such as oil of cloves, bergamot oil, creosote, turpentine, chloro- 

 form, &c. But with tender objects, particularly those with larger 

 or smaller internal cavities, the process is often attended with 

 great difficulties, and in such cases collapse and shriveling can 

 only be avoided by giving the most careful attention to every 

 step in the process. 



Dr. Giesbrecht recommends, for difficult cases, chloroform, 1 as 

 it is one of the best, and at the same time the most volatile sol- 

 vent of paraffine. 



(2) Transferring from Chloroform to Paraffine. — After the 

 objects have become thoroughly saturated with chloroform, the 

 containing tube is placed on a water bath and heated to about 

 50 C. — the melting point of paraffine ; then a small piece of 

 paraffine is added and allowed to dissolve, and this is repeated 

 until bubbles cease to rise from the objects. To make sure that 

 the chloroform has been fully expelled, the objects may next be 

 transferred to pure paraffine and left for a few minutes before 

 imbedding. 2 



(3) Shellac as an aid in Mounting.— -The use of shellac for fix- 

 ing sections on the slide, introduced by Dr. Giesbrecht, 3 is a very 

 valuable addition to histological methods. By this method hun- 

 dreds of small sections may be arranged in serial order, and all 

 inclosed in balsam under the same cover without danger of dis- 

 arrangement. The method is further extremely useful in mount- 

 ing larger sections, particularly those composed of loose parts, or 

 parts liable to swim apart. 



'IKitsdili Biolog. Centralblatt, II. I, p. 501) has also recommended chloroform, 

 entirely overlooking, as it would seem, Yn. < iic-brechfs prior publication. 



"For the Ilydro/oa, Professor Weismann prefers turpentine to chloroform, as 

 " ,ur * t 1 " letter lias been used, tin j trine is liable to be more or less spongy in 



