MOUNTING AND PREPARATION OF OBJECTS. 63 



belief is that they are hemispherical tuberosities, in 

 the diatomaceEe proper. Their markings possess little 

 interest now, since they are allowed to have no value 

 even as tests, for resolving power of objectives ; in 

 fact the investigation of their structure has led to 

 such a mis application of talent and waste of time, 

 that the majority of workers in science have handed 

 this department over to the amateur. 



Botanical preparations require considerable care in 

 their preparation, and as a rule are best examined in 

 the fresh state. A few, such as sections of stems, 

 etc., may be mounted in glycerine and a thick solu- 

 tion of gum in camphor water. Opaque objects as 

 soii of ferns, may after soaking in turpentine be 

 mounted in balsam • but others require a process of 

 maceration, staining and dissection, which will be 

 best understood by a reference to some text-book on 

 botany. 



Pathological and histological objects are prepared 

 and mounted by the following methods. 



When the intimate structure of tissue requires in- 

 vestigation, it should be obtained as fresh as possible 

 and a small portion immediately teased out with 

 needles, in a little serum or glycerine on a glass 

 slide. It will be found advantageous to insert the 

 needles into light wooden handles with a pliers, and 

 to place a piece of black cloth or white paper under- 

 neath the slide during dissection. When the dissec- 

 tion is finished, the tissue is steeped for three minutes 

 in a i p.c. solution of chloride of gold, or a small 

 quantity of the toning solution used for prints 

 diluted with three or four times its weight of dis- 



