GENERAL ORGANIZATION 



757 



notnyxon, HexactinoDiyxon, Triactinomyxon, Synactmomyxon, and Sphcerac- 

 tinomyxon, which differ from one another in the character of the spores 

 and other details. 



According to the observations of Mackinnon and Adam (1924) on 

 Triactinomyxon legeri in Tubifex tubifex, the life-history is as follows 

 (Fig. 325) : The pansporocyst, a spherical cyst of about 60 microns in 

 diameter, contains eight closely packed spores, the three tails of which are 



Fig. 324. — Spores of Various Actinomyxidiida. (From Caullery and Mesnil, 



1905, AFTER StOLC, LeGER, AND CaULLERY AND MESNIL.) 



I. II exact inomyxon psammorocj/stis ( x 450). II. Triactinomyxon ignotum ( x 250). 



Ila. Terminal portion of i^ipore of T. ignotum, showing eight " sporozoites " and three jiolar 

 cap.su les ( x 900). 



III. Synactinomyxon tubificis. A, Surfacs view of spore with three polar capsules; B, side 



view of spore ( x 900). 



IV. Sphceractinotnyxon stole i. A, Side view of spore; B, end view, showing three jjolar capsules 



( X 900). 

 g, Germinal mas.s; sp.., " sporozoite "; ti.e, nucleus of envelope cell; n.ii, nucleus of polar capsule 

 cell; u, polar capsule. 



folded within the cyst membrane. By rupture of the cyst the spores are 

 liberated when the tails become extended, and the characteristic tri- 

 radiate arrangement is seen. The individual spore varies in size. Its 

 length up to the point where the three rays originate varies between 

 90 and 140 microns, while its breadth varies from 11 to 16 microns. The 

 rays also vary in length, but on an average this is 150 microns, while the 

 breadth is 8 to 14 microns. At the end of the spore are three polar capsules, 

 from which filaments can be extruded, while adjacent to them is a mass 



