282 



BIOLOGY OF THE PROTOZOA 



single cells of the colonies are built on the same plan as the Chlamy- 

 domonadida? with 2 (rarely 4) equal flagella, non-metabolic body 

 a simple contractile ^'acuole, chromatophores, stigmata and cellu- 

 lose walls. 



Asexual reproduction occurs in the individual cells within the 

 cellulose membranes and results, usuallv, in the formation of a new 





-f 



^ 



Fig. 136. — Volvox globator (A) and V. aureus (B, C, D). A, Sexually mature colony 

 with eggs (e, macrogametes), and spermatozoids (s.p.) ; B, asexual colony with young 

 agamous daughter colonies; C, female colony with macrogametes; D, male colony, 

 with many bundles of spermatozoids (microgametes) . (From Oltmanns.) 



colony from each cell. In some cases all individuals of the colony 

 thus reproduce the whole (Goniuvi, Spondylovwrvm , etc.) but in 

 others the individual cells of the colony are differentiated into 

 "somatic," and "generative" cells, the latter alone reproducing 

 (Pleodorina, Volvox, etc.). 



Starting with the genus Spondyloniontm of the preceding family, 

 the different colonial aggregates form a series of increasing com- 



