64 COCCOPHYCE.E. 



Popular Science Review, vol. v. p. 137. A. W. Wills in 

 Midland Naturalist, Sept.- Oct., 1880. A. Bennett in Popular 

 Sci. Rev. 1878, p. 225. 



Sphcerosira volvox, Ehr. Infus. (male). Pritch. Infus. p. 

 526. Williamson in Popular Sci. Review, vol. ix. p. 225. 



Volvox stellatus, Elir. Infus. (oospore). 



In clear pools, ponds, &c. 



The relationship of Sphesrosi/ra -rolwx to Volrox globator has not been 

 satisfactorily determined (see Williamson), although there remains no 

 doubt of the existence of relationship. Some regard it as the male 

 form, but Professor Williamson considers it a peculiar condition of 

 Volvox. 



For details of a successful experiment in keeping Volvox during the 

 winter see N. E. Brown in Gardener's Chronicle (1879 p. 599) and 

 " Ponds and Ditches," by M. C. Cooke, p. 63. 



Plate XXII. jigs. 1-3. Volvox globator, after A. W. Wills; 4-5, after 

 Cohn. Explanation given above. 



Plate XXIII. figs. 1-5. After A. W. Wills; 6, ideal section after 

 Williamson ; 7, after Wills also fully described above ; 8-9, X 300 

 after Stein; 10, complete antheridium ; 11, stellate resting spore or 

 oosphere X 400 ( Volvox stellatus) 12, spermatozoids X 600. 



Plate XXIV. Male plants of Volvox, known as Spheerosira volvox, 

 after Williamson. Fig. 1, coeuobium ; 2, protoplasmic mass from the 

 coenobium, containing granules ; 3, mass divided in two ; 4, the same 

 divided into four; 5, the same divided into sixteen; 6. further division 

 into thirty- two, provided with movable cilia ; 7, discoid family revolving 

 within its mother-cell. 



Volvox minor. Stein Infus. p. 47. 



Ccenobia and the number of cells smaller ; the number of 

 daughter-ccenobia evolved without sexuality within the mother, 

 1-9 ; fructification sexual, monoecious ; many male cells 

 changing into bundles of spermatozoa; 5-10 female cells in 

 the same ccenobium, after fecundation, evolved into as many 

 oospores, surrounded by a smooth epispore (=Volvox aureus, 

 Ehr.). 



SIZE. Variable, but smaller than the preceding. 



Rabh. Alg. Eur. iii. 98. Stein Infus. t. 



Volvox globator, of authors, in part. 



Volvox aureus, Ehrb. Inf. 71, t. 4, f . 2 (oospore). 



In similar places to the preceding. 



Plate XXV. Volvox minor X 400 after Stein. Fig. 1, portion of 

 ccenobium with two young daughter families ; 2, coenobium with two 

 young daughter families enclosed in mother-cell ; 3, coenobium with five 

 young fertile cells ; 4, ccenobium wi^h six young fertile cells ; 5, a fer- 

 tile cell enclosing numerous vacuoles indicating the commencement of 

 subdivision ; 6, isolated daughter-family still enclosed in the mother- 

 cell ; 7, encysted cell the Volvox aureus of Ehrenberg j 8, isolated 

 ordinary individual enclosed in a flask-shaped cell. 



