Page 67 - My FlipBook
P. 67
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organisms, are very particular as to the temperature in whiclT
they grow, some not growing well except at the body tem-
perature of the animal in which they are parasitic ; for in-
stance, those that are parasitic in man, some of them will not
grow well unless they are at about the temperature of
98—they will bear a few degrees either way, but not very
much. Others will grow close down to the freezing point.
Classification of Micro=organisms.
In order that you may read intelligently it is necessary
that you get the meaning of the following terms perfectly,
because they are terms that are continually in use in the
books :
Micro-organisms are divided into two great classes :.
Saprophytes and Parasites.
Saprophytes are those that grow commonly only in dead'
organic matter.
Parasites are those that grow commonly in living organic
matter, that grow in animals or plants.
In medical bacteriology we pay no attention whatever
to micro-organisms parasitic upon plants, and when upon
this subject we speak of parasitic micro-organisms we always-
allude to those that are parasitic in animals.
The saprophytes are divided into strict saprophytes and"
facultative parasites.
Now, this word -facultative is a stumbling block ; I don't
like the word myself, but it is the word in general use, and
we have to use it. It comes from the Latin word facultas
to make, or to be able to do—and as it is used here it means
the ability to become—the saprophyte that has the ability to-
become a parasite we call a facultative parasite. There are
many of these ; many of the micro-organisms that we find*,
growing habitually as saprophytes, or growing in dead or-
ganic matter, will, if occasion offers, grow as parasites. Some
of our most violent diseases are caused by these. The micro-
organism of tetanus is found growing in the earth ; it is a
saprophyte, and yet, upon occasion it will enter a wound ancf
grow as a parasite and produce the disease known as tetanus.
It is indigenous in the soil of some localities ; it is found very^
sparingly here in Illinois, and we only occasionally hear of a
case of tetanus ; on Long Island it is more abundant, and
53
organisms, are very particular as to the temperature in whiclT
they grow, some not growing well except at the body tem-
perature of the animal in which they are parasitic ; for in-
stance, those that are parasitic in man, some of them will not
grow well unless they are at about the temperature of
98—they will bear a few degrees either way, but not very
much. Others will grow close down to the freezing point.
Classification of Micro=organisms.
In order that you may read intelligently it is necessary
that you get the meaning of the following terms perfectly,
because they are terms that are continually in use in the
books :
Micro-organisms are divided into two great classes :.
Saprophytes and Parasites.
Saprophytes are those that grow commonly only in dead'
organic matter.
Parasites are those that grow commonly in living organic
matter, that grow in animals or plants.
In medical bacteriology we pay no attention whatever
to micro-organisms parasitic upon plants, and when upon
this subject we speak of parasitic micro-organisms we always-
allude to those that are parasitic in animals.
The saprophytes are divided into strict saprophytes and"
facultative parasites.
Now, this word -facultative is a stumbling block ; I don't
like the word myself, but it is the word in general use, and
we have to use it. It comes from the Latin word facultas
to make, or to be able to do—and as it is used here it means
the ability to become—the saprophyte that has the ability to-
become a parasite we call a facultative parasite. There are
many of these ; many of the micro-organisms that we find*,
growing habitually as saprophytes, or growing in dead or-
ganic matter, will, if occasion offers, grow as parasites. Some
of our most violent diseases are caused by these. The micro-
organism of tetanus is found growing in the earth ; it is a
saprophyte, and yet, upon occasion it will enter a wound ancf
grow as a parasite and produce the disease known as tetanus.
It is indigenous in the soil of some localities ; it is found very^
sparingly here in Illinois, and we only occasionally hear of a
case of tetanus ; on Long Island it is more abundant, and
53
