Observations on the Genus Volvox in Africa. 431 



from one another in F. aureus before escape ; in V. globator they are 

 still in contact at this stage. 



5. The diameter of the daughter colonies on escape is from 200 to 

 250 p in F. aureus ; 150 to 200 /x (rarely to 320 /JL) in V. globator. 



6. The protoplasts of the somatic cells in F. aureus are almost 

 round in surface view, more oval in side view ; in F. globator they are 

 smaller, more closely packed, rather angular in surface view, and 

 flattened basally in side view. 



7. The protoplasmic processes are very delicate in F. aureus ; in 

 F. globator they are thicker, and continuous with processes from the 

 angles of the protoplasts (the chloroplasts extend into these processes). 



8. The sexual colonies in F. aureus may be exclusively male or 

 female, i.e. dioecious, or they may be monoecious, and may or may 

 not contain daughter colonies as well ; in F. globator they are almost 

 invariably monoecious (i.e. they contain both antheridia and oogonia), 

 and do not, as a rule, contain daughters. 



9. The antheridia in F. aureus are numerous (as many as two- 

 thirds of all the cells may form sperm bundles) ; in F. globator there 

 are only from about 5 (or fewer) to 15. 



10. The sperm bundles measure from 12 to 18 ^ in diameter in 

 F. aureus, from 23 to 34 /j, in F. globator. 



11. Each sperm bundle is composed of 16 or 32 spermatozoids in 

 F. aureus, from 64 to 256 or more in F. globator. 



12. The spermatozoids in F. aureus have a spherical nucleus and 

 terminal cilia ; in F. globator they are more slender, with an elongated 

 nucleus, and the cilia may be either laterally or terminally attached. 



13. The oospores in F. aureus number from 1 to 15 (usually 3 to 8) ; 

 in F. globator they number from 12 to 69 (usually about 30). 



14. The oospore in F. aureus measures from 60 to 75 JJL in diameter, 

 and its outer wall is smooth ; in F. globator it measures from 44 to 56 JJL, 

 and its outer membrane, when ripe, is covered with conical spines. 



15. A still more fundamental difference between the two was 

 demonstrated by Meyer * during an investigation into the structure 

 of the membrane of the coenobium. In F. aureus the somatic proto- 

 plast is embedded in a thick gelatinous wedge-shaped mass extending 

 far into the interior of the colony, where the radial walls join a central 

 massive star-shaped body (see fig. 1, AJ ; in F '. globator it is enclosed 

 in a short five- or six-sided gelatinous prism tapering very slightly 

 towards the interior of the coenobium from which it is delimited 



* Meyer, A., " Die Plasmaverbindungen und die Membranen von Volvox, etc.," 

 Bot. Zeit., vol. liv, 1896, p. 187. 



