ON COLLECTING, PREPARATION . AND MOUNTING. 383 



pared insect while under the influence of chloroform for specific 

 characters. 



In giving a short account of the preparation of Scale-insects for 

 the cabinet and the microscope, I am not only indebted to Newstead's 

 valuable Monograph, but to personal assistance from Mr Newstead 

 himself long before the book was published. 



For cabinet purposes, and for the study of external characters, 

 where the number and variety of species are the chief objects in view, 

 small cork slips of 3 inch x 1 inch, and covered with white or black 

 paper, according to the colour of the species, may be used. Put 

 where it is intended to display the " scale " from an educational point 

 of view, together with the nature of the damage it causes and the 

 more salient details of structure, a suitable space should be allotted 

 to it in the cabinet. 



As, however, the scales are almost exclusively a microscopical 

 study, it is indispensable to give a short account of the necessary 

 preparation. In scale - insects we have two great divisions. one 

 where the body is protected by the scale, the other where the actual 

 body is the scale itself. The former class is well represented by the 

 Diaspinse, Pseudococcus, &c. ; the latter by the Lecanium and Pul- 

 vinaria. Now let us begin with the Diaspinse, and no better example 

 could be taken than. the Chionaspis on ash, willow, &c, as found in 

 winter. Under a weak lens, reading-glass, or arrangement as in fig. 

 348, lift up a female scale, and underneath this we find the dead 

 female surrounded by eggs. Collect a number of those female insects, 

 and place them in a saucer of water. Be it remembered they are 

 mere tiny specks, and can only be lifted with a needle or woodcock's 

 feather. Xow we must boil it in, say, a ten per cent solution of 

 caustic potash (KOH). The strength need not be too accurate, 

 about two penny sticks in a pint of water would do. Place the 

 insects in a portion of this solution contained in a very small tube, 

 and stoppered with cotton -wool. Place this small tube inside a 

 larger one, containing water, and boil the two tubes in a small 

 enamelled cup over a spirit-lamp for about fifteen minutes. Pour out 

 the boiled insects from the inner tube into a saucer of clean water, 

 pick them up with a needle, and re-boil them in clean water for a 

 short time, transfer them to dilute and then to absolute alcohol, and 

 from this again transfer them into another glass containing absolute 

 alcohol and a weak colouring of one of Crawshaw's dyes, which 



