so LLINOIS BIOLOGICAL MONOGRAPHS [288 



DEFINITION OF TERMS USED FOR DESCRIPTIONS 



Anterior end. — The end of the spore where the polar capsules open; in most 



cases the polar capsules are situated at this end. 

 Anterior process. — The spinous process of the shell at the anterior end of 



the spore of the genus Myxoproteus. 

 Breadth. — The larger diameter of the spore measured at right angles to the 



length or sutural diameter; the shorter diameter thus measured being 



the thickness. 

 Capsulogenous cell. — A small island of protoplasm with a nucleus, in which 



polar capsule becomes differentiated. 

 Cyst. — The vegetative form of more or less conspicuous size in tissues of the 



host, surrounded usually by a membranous structure composed of the 



host issue. 

 Disporous. — The character of a trophozoite of forming only two spores. 

 Foramen. — Opening of the polar capsule thru which the polar filament is 



extruded. 

 Front view. — The view in which length and breadth of the spore are laid 



horizontally. 

 Gemmules. — A small mass of trophozoite separated from the mother body 



by plasmotomy. Used by Davis (1917). (See page 105.) 

 lodinophilous vacuole. — The vacuole in the sporoplasm of the spore of the 



family Myxobolidae, the contents of which are stained brownish with 



iodine. 

 Lateral process. — The lateral prolongation of the shell-valve at right angles 



to the sutural plane. 

 Length. — Antero-posterior diameter of the spore in the sutural plane; 



equivalent to sutural diameter. 

 Longitudinal striations. — Fine ridges or thickenings marked longitudinally 



on the shell of the spore. 

 Mesoplasm. — An intermediate layer between ectoplasm and endoplasm, 



coined by Cohn in the case of Myxidium lieherkiihni (see page 107). 

 Mictosporous. — The character of the trophozoite of forming a variable 



number of spores in an individual. 

 Monosporous. — The character of the trophozoite of forming a single spore. 

 Pansporoblast. — Coined by Gurley (1893:408) used here in the same mean- 

 ing, an enclosed area in the endoplasm of the vegetative form, in which 



two sporoblasts become differentiated. 



