B58 THE AMEEICAN MONTHLY [Nov. 



is simply moved backwards and forwards upon the glass over 

 the paste. By means of the Vienna chalk you can polish your 

 knife in a very few minutes. The diamantine allows you to put 

 a sharp edge on it, but does not give a polished surface, but 

 rather a rough one. Now, when you have a knife which is 

 highly polished, you can cut a section of, say, 5 mm. perfectly 

 well; but if you try to cut with it a section of 1 to 2 mm., 

 you will not succeed at all ; your sections will become com- 

 pressed and wrinkled, and you can do nothing with them. On 

 the other hand, if you try to cut a section of 5 mm. with a 

 knife having a rough surface, your section rolls up. This roll- 

 ing up of a section has been represented to be a fault in the 

 paraffin, but that is not the case. We must adapt the knife to 

 every thickness of section we wish to cut. Starting out with 

 a certain knife, if your section curls up, the proper thing to do 

 is to polish your knife with Vienna chalk, and your section for 

 that thickness will not curl up any more. If your section be- 

 comes too much compressed, your knife should be rubbed over 

 the diamantine and the polished surface taken away, when the 

 sections will be cut without compression." — Johns Hopkins Hos- 

 jntal Bulletin. 



Preservation of some Marine Animals. — Mr. W. A. Red- 



enbaugh says that while spending a few weeks at the U. S. Fish 

 Commission Laboratory at Wood's Holl, Mass., he obtained 

 some interesting results with Epsom salts in the preservation of 

 many marine invertebrates. "The method of application re- 

 quires modification in individual cases, but a few experiments 

 will usually enable one to obtain the desired results. . . Com- 

 plete stupification of the organism must be produced, so that 

 when it is removed to a killing fluid no contraction will take 

 place. Care should be exercised, however, not to carry on the 

 process too slowly, as maceration may ensue. 



Ccelenterates. — The most beautiful results were obtained with 

 sea-anemones, which ordinarily are so difficult to preserve in a 

 well expanded condition. These were allowed to expand in a 

 dish with as little water as possible. The crystals of magnesium 

 sulphate were placed in the bottom of the dish and allowed to 

 dissolve slowly until a saturated solution was obtained. The 

 process of dissolving may be hastened, if necessary, by stirring 



