14
The daily variations in the percentage of chlorides in the serum of this goat were
also estimated (for method vide Bulletin 1, page 30).
Mean of 14 day
. . .
...
...
. . .
... 64 per cent. NaCl.
Highest observation
...
...
...
...
...
...
67 per cont.
„
Lowest
. ..
. . .
. .
. ..
. . .
. . . 61 per cent. „
Chart 1 shows the daily variations in the resistance of the erythrocytes of a .
healthy goat to lysis by hypotonic salt solution for a period of 14 days together with
the variations in the percentage of chlorides contained in the serum of the same
animal.
The range between the first noticeable "trace" of lysis and "complete" lysis
seems to remain about the same ; that is to say, as far as can be judged by this some- -
what rough visual method, if on any particular day there are more erythrocytes in the
circulation which are less resistant to the highest percentages of salt employed there
are also fewer which are resistant to the lowest percentages of salt employed.
The range between the "trace" and "complete" points appears to be much the
same in all the species of animals so far tested, though each species occupies a definite
position on the percentage scale, but into this matter we hope to enter more fully in a
subsequent issue.
Suffice it to say at present that the vast majority of the erythrocytes of any
healthy animal are lysed completely by lowering the tonicity of the suspending fluid
to a certain point ; that comparatively few are more resistant or less resistant than the
majority ; that variations from the mean are measured by actually small differences i n
the tonicity of the suspending fluid and that the fluctuations in resistance from day to
day seem to effect the whole number of the erythrocytes.
There appears to be no obvious relation between the fluctuations in resistance of
the erythrocytes and the percentage of chlorides present in the serum. ( Vide chart 1.)
We have not touched upon variations in resistance resulting from disease but a
careful experiment made by dieting two puppies seems to show that, as long as no
actual organic disease is engendered, unsuitable diet carried nearly to the extent of arrest
of growth has no influence on the resistance of the erythrocytes.
Two healthy puppies, 3 months old, from the same litter were selected and the
lytic points of their erythrocytes determined. One was then fed on an exclusively
meat diet, the other on an exclusively vegetable diet. During the period of the
experiment "Meat" increased in weight by 66 per cent. while "Vegetable" only
increased by 5 per cent.
After 21 days dieting the lytic points of the erythrocytes of both animals were
precisely the same as they were before the dieting began. After 32 days there was a
slight fall in resistance in both animals but it was the same for each.
" Meat"—
Before dieting.
After 21 days.
After 32 days.
Weight in grammes ... 2,300
2,970
3,830
"Trace" lysis
...
.510 per cent.
.510 per cent.
.527 per cent. NaCl.
"Complete" lysis
...
.374
„
.374
. 391 „
" Vegetable "--
Weight in grammes ... 2,600
2,720
2,730
"Trace" lysis
...
. 510
.510 „
.527 „
"Complete" lysis
...
.374
„
.374
„
. 391 „
At the end of the experiment it was found that 62 per cent. of "Meat's" serum in
a total volume of 2 .0 cc. was required to completely dissolve 0 . 05 cc. washed human
erythrocytes and 52 per cent of "Vegetable's" serum.
It may be concluded, therefore, that the serum of an ill-nourished but otherwise
healthy animal may be expected to contain as much lysin as that of a well nourished
animal and that the erythrocytes of healthy animals of the same species will not be
found to vary as regards their lytic points beyond the normal range as a consqeuence
of poor feeding.