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 maybe 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 

 at random. 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. When ready 

 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 

 lias 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 in a 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 : 



