198 ON THE NATURAL HISTORY OF THE LAC INSECT. 



spot. The holes are situated triangularly with respect to each other, two 

 being closer together than the third, which is the largest, and which, by 

 and by, will be found to be the anal, while the other two will be found to 

 be spiracular apertures : all three are continuous, with corresponding aper- 

 tures in the insect, from which the white filaments originally proceed, 

 which filaments we shall hereafter observe to be the attenuated extremities 

 of the tracheae. If we now examine the contents of the interior, which we 

 may easily obtain entire by dissolving off the lac in spirits of wine (for, 

 from their tenderness, they can hardly ever be extricated without rupture 

 by simply breaking the incrustation), it will be observed that each cell is 

 filled with a single insect, which is now almost as much unlike one as any 

 object can well be unlike another — consisting of a pyriform sac of a dark 

 red colour, smooth, shining, and presenting at its elongated end one, and at 

 its obtuse end three papillary processes ; the former, which is a continuation 

 of the elongated end, is fixed to the bark ; and the three latter, which pro- 

 ject from the middle of the obtuse end, are respectively continuous with the 

 three holes in the lac above noticed. As with these holes so with the three 

 processes : one is much longer and larger than the other two, which latter are 

 of the same size ; the former is also further distinguished by having several 

 hairs round the margin of the aperture which exists at its extremity — a 

 point which it is desirable to remember, as it will serve by and by to 

 identify it with the anal extremity of the animal when in its insect form. 

 So far, the spirit of wine assists ; but when we come to the contents of the 

 body, it is not only necessary to avoid using spirit of wine, from the dis- 

 figuration which it occasions by causing the tissues to contract, but also to 

 extricate the body by fracturing the lac, and dissect its contents as quickly 

 as possible on account of the rapidity with which they pass into dissolution 

 after death : this is probably the reason why this part of the history of the 

 insect has remained unpublished up to the present time. Directing our 

 attention to the interior, after the rupture of the insect, which takes place 

 more or less with that of the lac, we are at once struck with the volumi- 

 nousness of the organ containing the red colouring matter, which organ 

 thus obscures everything else ; and it is not before a quantity of it is 

 removed by gentle edulcoration, that we can (still under water, for 

 the anatomy of this insect can be studied in no other way) arrive at a 

 view of the other organs of the body, when it will be observed that 

 there is an alimentary canal, liver, tracheae, and, last of all, the organ 

 containing the red colouring matter, which we shall presently find to be the 

 ovary. To each of these organs, then separately and briefly, we will now 

 give our attention. The alimentary canal commences with an attenuated 

 shapeless oesophagus at the elongated end of the body, which is thus seen 

 to be the oral extremity, and after passing upwards for about two-thirds of 

 the abdominal cavity, where it becomes enlarged and convoluted, turns back 

 to make a single revolution, in the course of which it soon becomes 

 diminished in calibre, and receiving the hepatic duct at this point, terminates 

 at length in the rectum, which opens at the great papillary process. The 



