TESTS OF THE STRENGTH OF SILK FIBRES. 69 
Here, as before, we have given the actual measurements taken, the 
strains being stated in grams and the stretch in millimeters and per 
cents. In the recapitulation we have prepared a statement showing 
the averages of all the measurements taken with each sample respect- 
ively, as well as the highest and lowest results obtained in each, the 
strain in each ease being reduced to grains and the stretch to per cents 
ot the length. This will make the figures more intelligible to all who 
may be interestedin them, and will render a comparison much more easy. 
In the lower lines we find a statement showing the number of measure- 
ments found above or below the average, as the case may be, for each 
sample. 
In explaining the method of measuring the fineness reference has 
been made to the peculiar structure of the fibre, resulting from the 
mode of itsproduction. This structure was decidedly marked in * dry ” 
No. V. Here very many of the fibres were split either before the test 
or became split by the strain or at the instant of rupture. We find 
upon comparison of the results obtained in the tests of the split fibres 
in tests of whole fibres from the same cocoons that the latter are very 
considerably stronger than the former, though as regards the percent- 
age of stretch there appears to be no very material difference between 
the two. And another peculiarity in the rejiations of the two is that the 
strength of the whole fibre appears from the averages to be about double 
that of the split fibres. Let us bring these averages together for more 
ready comparison. It will suffice to express the strain as grams: 
1 Split. | Whole, 
grams. | grams. 
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On the other hand it may ,.be mentioned that the uniformity in the 
strength of the fibres as regards the strain they are able to bear pre- 
vious to rupture, as represented in the number of measurements found 
above and below the averages respectively, appears to be greater in the 
split fibres. The most important difference appears therefore to be in 
the strain representing the strength of the fibre, showing the impor- 
tance of the more complete cementation of the fibres together as they 
issue from the spinnerets of the worms; and we may also learn from this 
something of the importance of maintaining the healthy and vigorous 
condition of the worms during their development, and more especially 
during the period when they are spinning their cocoons. The vigor 
and activity of the insects at the time may be very materially stimu- 
lated by careful regulation of the temperature, ventilation, and light, 
and not only the value of the fibre with this regard, but the condition 
and appearance of the cocoon, upon which its market value largely 
depends, may be modified by these relations. In this rather critical 
