94 ILLINOIS BIOLOGICAL MONOGRAPHS [332 



Vegetative form: Round or irregular. No clear differentiation of 

 protoplasm. Endoplasm highly vacuolated. Ectoplasm being hardly 

 distinguishable. Size up to 40/t in diameter. Trophozoites float in the 

 bile in almost all cases. Disporous and polysporous (up to 8 spores). 



Spore: Spherical, often attenuated at the anterior end. Sutural line 

 not straight. Shell very thick, shows thick ridges running longitudinally 

 on the surface. In optical cross section, the spore presents an outline like 

 a cog-wheel with 20 to 22 ridges. The thickness of ridges varies regularly; 

 the thickest ones being located on two lines where a plane perpendicular 

 to sutural plane cuts the shell longitudinally, others decreasing in thick- 

 ness as they approach the sutural line. Four polar capsules at the anterior 

 end. Sporoplasm with two nuclei. Dimensions: length 10 to 12jLt, breadth 

 8 to 10/i, polar capsules 2 to 3n, length of polar filament 23 to SOn (KOH). 



CHLOROMYXUM CLUPEIDAE Hahn 

 [Figs. 153 to 156 and 562 to 565] 



1900 Sporozoa Tyzzer 1900 : 66-^ 



1901 Sporozoa Linton 1901 : 438 

 1910 Chloromyxum sp. Auerbach 1910 : 178 

 1917 Chloromyxum dupeidae Hahn 1917 : 15-19 



Habitat: Body musculature of Clupea harengus, Pomolobus pseudohar- 

 engus, P. aestivalis, P. mediocris, Brevoortia tyrannus, Stenototnus chrysops, 

 Tautogolahrus adspersus; Woods Hole. 



Tyzzer mentioned in his paper and also in a letter to the writer that 

 he collected the material in August of 1900 and that he found the infection 

 occurred only among young fish. Hahn also called attention on the latter 

 fact. 



Vegetative form: Hahn's observations are as follows: 



Clusters of spores ("pseudocysts") are spindle-shaped, especially when 

 young, usually l5ang between the bundles of muscle fibres. Color white or 

 creamy. Larger ones usually "in pocket just beneath the integument." 

 Schizogonic multiplication probably exists. Parasites hard to stain, 

 anilin dyes being unable to stain at all. Large form (probably composed of 

 many individuals) 890ju by 30jli. 



Tyzzer described as follows: Cysts up tO" 1 to 2 mm. in length, lying 

 between the muscle fibres of the myotomes, surrounded at times by mem- 

 braneous connective tissue. The parasites also occur in diffused infiltration. 



Linton found two cysts, 1.74mm. by 1.16mm. and 1.16mm. by 0.58mm. 

 and also diffused state between the fibrillae. 



The writer's observation on slides prepared by Dr. Tyzzer* is as fol- 

 lows: Two cysts in sections; one almost spherical, 480/x by 430/x, sur- 



*The writer had recently the opportunity of examining the slides of the parasites prepared 

 by Dr. Tyzzer, which occasion he appreciated very much. As a result of this, the writer 

 became convinced of the identity of forms observed by Tyzzer, Linton and Hahn, tho he 

 could not examine the latter authors' specimens. 



