58 BULLETIN NO. 3, DIVISION OF ENTOMOLOGY. 
the same time there is danger that in taking the measurements with the 
microscope the longer axis of the fibre may be taken in some cases, while 
in others the shorter axis may be inadvertently chosen. So also it 
may to some appear extremely desirable that in order to fairly deter- 
mine the fineness of the fibre both axes should be measured, and there 
is much of reason in this opinion. On the other hand,if we bear in mind 
that the breadth of the ribbon will depend upon the diameter of-the in- 
dividual fibres constituting the raw fibre, it will be seen that the breadth 
of the fibre, or its longer lateral axis, may be accepted as a fair repre- 
sentation of the degree of fineness of this condition of the staple. 
The method of taking the measurements of fineness is therefore as fol- 
lows: The cocoon is cut open and separated into the different layers of 
which it is made up. A small tuft of fibres is then cut from each, taken 
atrandom. ‘These are then cut to suitable length and mounted upon the 
glass object slide for microscope, immersed in Canada balsam, and covered 
with a thin glass circle. When the cover is in place the slide is gently 
warmed and laid aside for the balsam to dry and harden. Whenready 
for the purpose each slide is placed upon the stage of the microscope, 
the fibres successively brought into focus, and the width of the image at 
its widest part measured by means of an eye-piece micrometer, which 
has been standardized by means of a stage micrometer graduated to centi- 
millimeters. The relative measurement taken in this way is reduced to 
the absolute standard and the result entered in the record. The object 
of taking the width of the image at its widest part is to obviate the 
danger of measuring the image of the fibre turned more or less with 
its edge toward the eye, a difficulty that would materially vitiate the 
result. 
In experiments made in this connection, as well as in the measure- 
ments of wools and cottons ina similar way, it has been found both ad- 
visable and necessary, in order to arrive at satisfactory conclusions con- 
cerning the property under consideration, to make measurements of at 
least thirty fibres in each sample. For purposes of comparison every 
measurement is entered upon the record, which is given in the following 
table: 
