16 



HARDWICKE'S SC 1 ENG E-G OS SIP. 



At one time the cultivator indulged in the vain 

 hope that Doryphora was a mere passer-by, that he 

 would do his worst, and then [move on, witbout 

 becoming a permanent nuisance. Others, again, 

 fancied that a hot summer.and autumn, followed by 

 along drought in the ensuing year, tended to 

 diminish its numbers. But it has been proved 

 incontestably that the diminution was only due to 

 the circumstance of many of the larvae perishing, 

 through being unable to enter the ground hardened 

 and baked by the great heat ; plenty were left to 

 continue the breed. 



Fig. IS. a. Colorado Beetle, i. Foot of ditto, c. Pupa of 

 ditto, d. Wing-case, enlarged. 



Of the many nostrums that have been employed 

 for the destruction of this beetle, one only has 

 shown itself to be of any value. I mean, dusting 

 the plants with the highly poisonous substance 

 Paris green,— a compound of arsenic and oxide of 

 copper. However, setting aside the dangers of 

 inhaling this deadly mixture while spreading it over 

 the fields, there is the additional peril of impregnating 

 the soil with it,— a peril which experiments carried 

 out at Washington iiave shown to be well founded. 

 There remains, therefore, only the plan of hand- 

 picking, day after day, the eggs, larva;, and beetle. 

 But even this operation requires considerable care ; 

 for the juice of the crushed insect and its larvae 

 produces bladders and blisters wherever it comes 

 in contact with the skin. If a wounded spot be 

 touched by it, severe inflammation ensues, which 

 is liable to pass into ulcers, and an application of it 

 to the eye endangers vision to a very serious 

 extent. 



Pig. 17, on page 15, gives an idea of the'.Colorado 

 Potato-beetle in its dilferent stages. The eggs 

 are of a deep orange-yellow. The larvae on first 

 emerging, are of a blackish hue, which passes 

 quickly into a dark red, with a slight orange tint. 

 On attaining their full size the colour varies 

 between orange, reddish-yellow, and flesh. At c, 



fig. IS, is shown the pupa; at a the perfect insect, 

 natural size ; a foot is portrayed at i ; a wing- 

 case considerably enlarged at d. The ground 



colour of the latter is creamy-yellow {rahm-gelb), 



with five black longitudinal stripes, of which the 



third and fourth unite at the base. 



Doryphora does not by any means confine itself 



to the potato. In places where that esculent is 



wanting, it will support itself on any other member 



of the Solanaceous order,— the Egg-plant {S. melon- 

 gena), the Tomato {S. lycopersicum) , or the Winter- 

 cherry {Phymlis viscosa). Indeed, in the northern 

 parts of Illinois and in Wisconsin— incredible as it 

 may appear— it has established itself in the cab- 

 bage-garden as readily as in the potato-field. 



State of Illinois. Pr. H. . 



CELLS POR MICROSCOPIC OBJECTS. 



THE introduction of the Binocular Microscope as 

 a popular instrument has rendered it desirable 

 to mount objects as much as possible in their natural 

 form, necessitating the use of a cell more or less 

 deep to contain them ; but the difficulty has been 

 to find a suitable material for their construction and 

 a secure mode of attaching them to the glass slide. 

 It is by no means improving to one's temper to have 

 a pet slide come to pieces through a gentle tap on 

 the table, or some other of the ordinary occurrences 

 incidental to the handling of them, yet it frequently 

 so happens, and has so often occurred to myself, that 

 every fresh slide coming into my possession, either 

 by purchase or gift, is invariably re-cemented to 

 make sure of its safety. Out of the great variety of 

 substances suggested, experience has led me to 

 adopt the use of three only,— paper, tiu, and glass. 

 The objection formerly made to the use of paper in 

 leading to the production of fungoid growths upon 

 the object and on the surface of tlie glass, has been 

 overcome by means of varnish ; and slides so pre- 

 pared, and purposely kept under the most unfavour- 

 able circumstances, are, after several years' probation, 

 still as perfect as ever. 



There are two ways in which paper cells may be 

 made; one, by coiling it into cylinders and cutting 

 off rings in the lathe, and the other, by "punching" 

 rings out of flat, sheets. The former serves well for 

 all depths above the thickness of a sixpence, while 

 the latter is most convenient for all others that are 

 required to be of less depth, and may be adopted 

 even for the thinnest writing-paper. The first- 

 named plan, however, may be dispensed with, as 

 rings of cardboard can be built up to any height 

 with very litllc trouble or loss of time. The great 

 difliculty hitherto has been in punching out these 

 rings so as to get them of uniform width, that is to 

 get one punch perfectly concentric with the other ; 

 but at length a " happy thought " occurred, that 

 has rendered this dilemma " a thing of the past." 

 It appeared obvious that, having punched out the 

 interior of the intended ring, the placing of a kind 

 of button in the aperture with a shoulder projecting 

 beyond, and the exact width of the circle required, 

 would guide the outer punch to its proper place and 

 give us the hoped-for result, which it has done most 

 completely. 



The first step would be to provide a series of four 

 1 or five punches of certain relative proportions, with 



