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A finer form of metals, indicated by enhanced lines in their spark spectra (which are also observed in the spectra of some stars), obtained at the highest available laboratory temperatures (Lockyer); as protocalcium, protochromium, protocopper, protonickel, protosilicon, protostrontium, prototitanium, protovanadium. --…

Having the most primitive character; in the earliest form; as, a protomorphic layer of tissue. H. Spencer.

A group of cells resembling a stoma, but without any true aperture among them.

buminous matter, and closely related to the vegetable alkaloids; a cadaveric poison. The ptomaines, as a class, have their origin in dead matter, by which they are to be distinguished from the leucomaines.

A dissecting instrument for opening the spinal canal. [Written also rachiotome.]

A contrivance for exhibiting and measuring the refraction of light.

An instrument which periodically or otherwise interrupts an electric current. Wheatstone.

A suborder of Medusæ which includes very large species without marginal tentacles, but having large mouth lobes closely united at the edges. See Illust. in Appendix.

One of the Rhizostomata.

One of the bony, cartilaginous, or membranous partitoins which separate the myotomes. -- Scler`o*tom"ic, a.

Scotomy.

Dizziness with dimness of sight. [Obs.] Massinger.

The young attached larva of Discophora in the stage when it resembles a hydroid, or actinian.

A division of ganoid fishes which includes the paddlefish, in which the mouth is armed with small teeth.

ophora having large free mouth lobes. It includes Aurelia, and Pelagia. Called also Semeostoma. See Illustr. under Discophora, and Medusa.

An instrument or apparatus for comparing and grading the sensitiveness of plates, films, etc., as a screen divided into squares of different shades or colors, from which a picture is made on the plate to be tested.

Of or pertaining to the nasal septum and the maxilla; situated in the region of these parts. -- n.

An artificial division of gastropods including those that have siphonostomatous shells.

Pertaining to the Siphonostomata.

Any parasitic entomostracan of the tribe Siphonostomata.