Page 73 - My FlipBook
P. 73
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see the divisions of the scale, and here you see the micro-
organisms between. (Note.—In the printed illustrations the
scale taken with the twelfth-inch lens is engraved in white
lines across the first illustration. The other pictures of the
scale are not shown in the printed illustrations.) This gives
you, I hope, a conception of the minuteness of micro-organ-
isms. You know what a millimeter is you have seen the
;
illustration of a millimeter in three different powers, work-
ing up to the power with which the picture of the micro-
organisms was made. In reading of micro-organisms you
will come across the word ''micron" frequently. The micron
is one one-thousandth of a millimeter; or, in other words,
there will be ten microns between these lines. You can
figure out pretty closely from observing and dividing these
in your mind into ten, how broad these micro-organisms are,
and you will find that they run about four-tenths of a micron
in diameter. These particular ones that we have here are
not quite as large as some of the growths of staphylococci.
They are rather a small organism of their species ; they vary
a good deal in size as to the condition of their growth some-
;
times they will be larger, sometimes smaller, but they gener-
ally run about one-half micron in diameter.
I want you to understand something of the difference
between the forms of micro-organisms and the forms of the
yeast fungus, and I will have a yeast fungus thrown upon
the screen that you may get an appreciation of the differ-
ence in size and the general difference in character.
(Changing slides. Fig. 2.) In the yeasts we have no di-
vision by fission whatever ; the multiplication is by budding.
For instance, here is a little bud ; it starts out from the wall
of the mother cell and grows and gets larger and larger.
Here is one just protruding; a little protuberence first of the
membrane, and then that grows larger and finally there is
a little bit of a neck and then it falls away and there are two
cells. Here (pointing out) we have a cell with several buds
with a bud out here and a bud out there and a bud out there
and this one budding again before that is separated
from the mother cell. In that way clusters of cells
are formed, hanging together. There may be twenty,
thirty or even more cells hanging together in one
group, or if the culture is not fresh they will have
61
see the divisions of the scale, and here you see the micro-
organisms between. (Note.—In the printed illustrations the
scale taken with the twelfth-inch lens is engraved in white
lines across the first illustration. The other pictures of the
scale are not shown in the printed illustrations.) This gives
you, I hope, a conception of the minuteness of micro-organ-
isms. You know what a millimeter is you have seen the
;
illustration of a millimeter in three different powers, work-
ing up to the power with which the picture of the micro-
organisms was made. In reading of micro-organisms you
will come across the word ''micron" frequently. The micron
is one one-thousandth of a millimeter; or, in other words,
there will be ten microns between these lines. You can
figure out pretty closely from observing and dividing these
in your mind into ten, how broad these micro-organisms are,
and you will find that they run about four-tenths of a micron
in diameter. These particular ones that we have here are
not quite as large as some of the growths of staphylococci.
They are rather a small organism of their species ; they vary
a good deal in size as to the condition of their growth some-
;
times they will be larger, sometimes smaller, but they gener-
ally run about one-half micron in diameter.
I want you to understand something of the difference
between the forms of micro-organisms and the forms of the
yeast fungus, and I will have a yeast fungus thrown upon
the screen that you may get an appreciation of the differ-
ence in size and the general difference in character.
(Changing slides. Fig. 2.) In the yeasts we have no di-
vision by fission whatever ; the multiplication is by budding.
For instance, here is a little bud ; it starts out from the wall
of the mother cell and grows and gets larger and larger.
Here is one just protruding; a little protuberence first of the
membrane, and then that grows larger and finally there is
a little bit of a neck and then it falls away and there are two
cells. Here (pointing out) we have a cell with several buds
with a bud out here and a bud out there and a bud out there
and this one budding again before that is separated
from the mother cell. In that way clusters of cells
are formed, hanging together. There may be twenty,
thirty or even more cells hanging together in one
group, or if the culture is not fresh they will have
61
