BOMBYX MORI. 469 



which the muscular parts of the feet and the edges of the rings are 

 attached. This muscular covering is for the motion of the body. 

 Round the whole is the cuticle or external covering : this cuticle they 

 change several times before they arrive at their complete size. In one 

 that I observed, I found it change three times, viz. June 11th, 16th, 

 and July 3rd. On the 9th it began to spin. It would appear that 

 the skin of the head separates from that of the trunk or body, not all 

 coming off in one piece. 



When these parts are completely formed, and the animal is full-sized 

 and healthy, it then begins to set about its changes ; and the first 

 process is that of enclosing itself in its own substance. When they 

 begin to spin their pod, they choose a corner or small hollow part, such 

 as they can reach with their heads, while they hold fast on the opposite 

 side with their posterior feet. The small threads are made to stick to 

 the sides of the body composing the corner, as also each thread in some 

 degree sticks to the other, where they come in contact. 



At the very beginning of their spinning they throw out the last 

 excrements mixed with a little yellow mucus. They begin at the cir- 

 cumference, or make the outer works, and go on towards the centre, 

 enclosing themselves, making their own cavity smaller and smaller. 

 Their first is composed of loose network, which serves as a basis, or 

 means of suspension, of the cell or enclosing chamber. These outer 

 beams are more or less in quantity in proportion to the distance of the 

 walls or abutments from which they begin. When the network is 

 sufficient to support the cell in the middle, and the enclosure becomes 

 small enough for their future habitation, then they begin to weave close, 

 hardly decreasing the size of the cell. They make this so close that the 

 light can hardly pass through it. 



When they have got the walls of their cells sufficiently thick, and 

 probably most of the mucus is expended, then they lay it on a little 

 looser, which makes a soft lining for the animal. The shape of the cell 

 is an oval ; and although they turn in every direction in making it, yet 

 when they have finished spinning, they either leave off with their head 

 at the wide end, or they turn their heads to it ; for there we always 

 find their head. They are about thirty- six hours in completing their 

 pods ; some more, some less, according to their strength. They now lie 

 pretty quietly in their cells about twenty-four hours longer, only having 

 a little vermicular motion within themselves, which begins at one end, 

 and moves on to the other ; and then they turn on their back or side, 

 before they emerge out of this state. It may be observed that they do 

 not all spin a cell for themselves ; those that do not, I suspect are not 

 healthy, for they do not produce such strong moths. While they are 



