539 Molecular physics.

=540 Chemistry.=
541 Theoretical.
542 Experimental.
543 Analysis.
544 _Qualitative._
545 _Quantitative._
546 Inorganic.
547 Organic.
548 Crystallography.
549 Mineralogy.

=550 Geology.=
551 Physical Geography, Meteorology.
552 Lithology.
553 Dynamical geology.
554 Europe.
555 Asia.
556 Africa.
557 North America.
558 South America.
559 Oceanica.

=560 Paleontology.=
561 Plants.
562 Invertebrates.
563 _Protozoa and Radiates._
564 _Mollusca._
565 _Articulates._