53 
which follow are from that pamphlet. A farther word on some of the 
properties of the cocoon filament and the general process of reeling is 
also given in order to make the descriptions which follow more intelli- 
gible. 
Thesilk-worm occupies, in general, about thirty days in passing through 
the period comprised between its birth and the fabrication of its cocoon. 
Most of this time is employed in eating, but about five days being con- 
sumed in passing through the molts. The food consumed during the 
last ten days is almost entirely employed in the formation of a fluid 
which fills the silk ducts and which goes ultimately to the fabrication of 
the silken thread of the cocoon. 
In the body of the larvae there are two of these ducts, each of which 
is connected with an orifice called a spinneret, which is situated in the 
lower lip of the insect. The larva in the formation of its cocoon throws 
out from these orifices two fine filaments covered with a natural glue. 
This glue serves to stick the two filaments together and to form them 
into what appears to the naked eye to be one compact thread. An ex- 
amination of this thread under the microscope, however, shows its 
double nature and its flattened section, whose width is three to four 
times its thickness. 
The first step taken by the worm, after it has found a con venient 
place to make its cocoon, is to throw out a system of threads designed 
to form a founda ion to the more compact pod. The tissue of this sys- 
tem is loose and is not apparently woven after any fixed plan. Once 
this foundation completed, the larva begins the constru ctiou of the 
stronger wall of its resting place, which is constructed of a firm felting 
laid on in figure-eight loops and in many distinct layers. Of these 
layers it is easy to recognize at least a dozen and to tear them apart 
but it is probable that in reality these might each be subdivided into 
many more but for the lack of instruments of sufficient delicacy. 
Taking the yellow Milanese races as a type, we find that it requires 
about 250 fresh cocoons to make a pound and that each contains about 
one thousand yards of thread. These cocoons, with the inclosed chrys- 
alides, contain, however, 6G per centum of water, which in the course of 
three or four mouths 7 drying will effectually evaporate. Of the total 
weight of these cocoons, again, but about 15 per centum is formed of 
silk, the balance being composed of chrysalides and the skins cast by 
the larvae in their transformation. Thus, were we to recover all of the 
silk contained in a lot of cocoons, it would not exceed 15 per centum of 
the total weight when fresh, or 33 per centum of the weight when dry. 
It is not, however, possible to accomplish such a result, both on account 
of the loss caused in getting hold of the end of the thread and from the 
fact that it is impossible to finish the reelingof a cocoon to its veryeud. 
Manufacturers rarely obtain more than one pound of silk for each three 
and one-half pounds of dry cocoons employed, and it is not uncommon 
