142 



Transactions of the Society. 



IV. — Mycetozoa. Comuvia Scrpula, a Species neio to Britain. 



By Jos. M. Coon. 



(Read October 17, 1906.) 

 Plates X. and XI. 



Among some gatherings of sporangia made towards the end of 

 April 1906, from a heap of spent tan at Grampound, Cornwall, 

 some plasmodicarps of C. scrpula were found, and submitted to 

 Mr. A. Lister, who, in writing respecting them, says, " It is the 

 first record we have of its being found in Britain." From this and 

 subsequent gatherings, all stages of the organism have been found 

 or cultivated, enabling a complete description to be given. Previous 

 descriptions are limited to the mature plasmodicarp and its contents. 



Besting Spores. — Beginning with the resting spore (plate X. 

 fig. 1), we find it yellow, spherical, covered with markings or ridges 

 forming a somewhat irregular network, the meshes of which are 

 chiefly pentagonal or hexagonal in shape ; these ridges or mark- 

 ings appear to be folds of the spore-walls, formed doubtless 

 under some definite impulse on the slu-inking of the spore con- 

 tents on ripening. Seen in optical section, the spores appear to 

 have a border about 1 /i broad, but this is only an optical effect. 

 The diameter of the spores is from 10-12 yu. over the ridges. 



Swarm Cells. — About 12 hours after placing some of the spores 

 in water some had hatched, some were emerging from the spore- 



EXPLANATION OF PLATES X. AND XI. 



Fig. 1. — Resting spore, x 1200. 

 2. — Swollen spore, x 1200. 

 3. — Hatching spore, x 1200. 

 4.— Swarm cell, x 1200. 



5. ,, Beak developing, x 1200. 



6. „ . With flagellum. x 1200. 

 7. — Plasmodium, only partially extended, x 17. 

 8. — Sclerotium. x 17. 

 9. — Plasmodium. Feeding formation, x 19. 



10. „ Foraging formation, x 19. 



11. — Plasmodicarp. Immature, x 9. 

 12. — „ Mature, x 9. ' 



13.— Elaters. Forming, x 600. 

 14. „ Mature, x 520. 



15. — Nuclei, with protoplasmic strands connecting with peripheral pro- 

 toplasm. X 600. 

 16. — Mitosis. Immature plasmodicarp. x 720. 

 17 and 18. — Formation of elaters. 

 19. — Immature cell-wall. 



