Glossary - The Origin of Individuals - page 215

Haematopoietic cells : Blood cells.
Heat motion : See Thermal agitation .
Hylemorphic ontology : Ontology according to which things are the
result of two first principles, matter and form (see Aristotelism ,
Essentialism ).
Immunology : Discipline which studies immunity, i.e. the capacity of
an organism to resist and rid itself of an agent which is foreign to
it, e.g. a virus. There are two types of immunity. Humoral immu-
nity involves the secretion of antibodies by B lymphocyte cells.
These antibodies are proteins (immunoglobulins) which react with
a part of the infectious agent (the antigen) by complexing, neutral-
ising and eliminating it. Cell-mediated immunity involves the action
of T lymphocyte cells which, owing to the receptors situated in
their cell membrane, directly recognise antigens and neutralise
infectious agents.
In vitro : Experimentation outside a living system, e.g. a biochemi-
cal reaction produced in a test tube.
In vivo : Experimentation performed on a living organism.
Kinase : Post-translational modification enzyme phosphorylating
(adding phosphorus to) proteins (see Protein synthesis ).
Lymphocyte : See Immunology .
Macroscopic : Seen with the naked eye. A phenomenon can be
analysed macroscopically (at our level of observation) or at the
molecular level. For example, the rain which falls from clouds in
drops as we see it, is also behaving as a population of molecules of
water.