EEPORT OF THE ENTOMOLOGIST. 225 



the chrysalides arc mature, which is easily seen by their eyes becoming 

 black and the eggs harder to break under the pestle, and also that some 

 of them are turning into moths; we proceed to the definite examination. 

 We crush, one by one, the moths which have come out and the chrysa- 

 lides which remain, and search for corpuscles; the per cent, which is 

 thus found will not differ materially from that which exists in the 

 whole lot.''* 



The examination of the chrysalides here mentioned may bo made in 

 the manner already described when searching for the ferment of llac- 

 cidity and at the same time. 



Proceeding now with stock of which the purity has been ascertained 

 by one or more of the different methods of observation above described, 

 200 cocoons sliould be selected for each ounce of eggs that it is desired 

 to ])roducc. In making this selection great care shonld be exercised in 

 taking only cocoons that are fine in texture and firmly made. This 

 fineness is one of the prereqaisites of a first-class cocoon. What is 

 meant by this difference in texture will be seen by an examination of 

 Plato IV, Figs. 3 and 4, the former being fine and tlie latter coarse. 

 The firmness of the cocoon, dci)ending as it does on thu amount of sillc 

 which it contains, is an indication of the vigor of the worm and another 

 item to be considered in selecting stock for reproduction, liules have 

 been given for the determination of the sex of the inclosed insect, and 

 among them, perhaps the most common, is the assertion that those 

 that are cojistricted at the middle (Plate IV, Fig. 3) contain males, while 

 those not constricted (Fig. 4) contain females. This, however, may be 

 regarded as an indication rather than a fixed rule, and there are races 

 in which the cocoon is almost uniformly constricted and others where 

 the reverse is true. But this careful selection for sex is comparatively 

 unimportant, and we consider it wiser to choose the cocoons in relation 

 to their firmness and texture and trust to chance to bring as many male 

 moths as female. Double cocoons, where two worms have spun to- 

 gether, should never bo used in egg-making. 



The i)roper cocoons having thus been selected they sliould be strung 

 upon stout threads about 3 feet long. Care should be taken not to 

 prick the chrysalides with the needle while passing it through the end 

 of the cocoon in making the chains. These chains should then be hung 

 in a cool, darkened room, while waiting for the moths to emerge. They 

 should not be placed near any object which would be soiled b.y the 

 secretions emitted by the moths on their emergence from their cocoons. 



Previous to this emergence there should be prepared for each ounce 

 of eggs to be produced, about one hundred small bags of fine muslin 

 (cheese cloth makes a good material), made in the following manner : 

 Cut the cloth in pieces 3 by G inches, then fold one end over so as to 

 leave a single edge of about three-quarters of an inch, as shown in Plate 

 IV, Fig. 1. This should be sewn up into a bag with the upper end open 

 and then turned inside out so that the seams will cause the sides to 

 bulge. Thus completed they are called " cells." The cells should be 

 strung on a cord stretched across the room. Some trouble having been 

 experienced in keeping the moth from crawling out of the cell at either 

 side of the pin, which is the method of closing it shown in the figure, 

 the scheme shown in Plate IV, Fig. 2, was adopted in this office. This 

 consists in clamping the bags in fours between two sticks of wood, rough 

 sawn, about one-half by one-quarter inch through, and 14 inches long. 

 They are bound together by rubber bands and may be laid across par- 



" Maillot, Lemons, ^c, p. 250. 

 15 AG — '85 



