Bacteriology
that branch of biology which treats of bacteria. The study of these microscopic organisms has developed into one of the most important branches of modern biological science.
BACTRIA (bac'trē-a), a province of the ancient Persian empire, lying N. of the Paropamisus (Hindu Kush) Mountains, on the upper Oxus. A northern branch of the same range separated it from the Sacæ, and it had Sogdiana on the N. and Ariana on the S. It thus corresponded pretty nearly with the modern Balkh. Here many scholars locate the original home of the Aryan or Indo-European family of nations. Its capital, Bactra, or Zariaspa, was also the cradle of the Zoroastrian religion.
It maintained its independence until its subjugation by Cyrus about 540 B. C., when it became a satrapy of the Persian empire. It was included in the conquests of Alexander, and formed a part of the kingdom of the Seleucidæ until the foundation, about 256 B. C., by Diodotus, of the Greek kingdom of Bactria, which extended to the Indus, and which, after a long struggle, was overthrown by the Parthians.
BACTRITES (bak'trites, or bak-tritēs), a genus of fossil ammonitidæ, with a straight shell, and indented, but not ramified septa. The genus ranges from the lower silurian to the devonian.
BADEAU BACULITES (bak-ū-lītēs), a genus of fossil ammonites, characteristic of the chalk, having a straight, tapering shell.