SEXUAL PHENOMENA IN THE PROTOZOA 



217 



formation may take place in an isolated individual, and in this case, 

 at least, reproduction cannot be dependent upon sexual union or 

 conjugation, although it does not signify that conjugation is not nec- 

 essary for the continued power of reproducing. Kent ('81), who has 

 confirmed Cienkowsky's ('65) observations upon conjugation of Bodo 

 augustatus, states that a difference exists in the number of spores that 

 are formed in the fusion and in the solitary cysts, only four spores 

 arising from the latter. 



A significant feature in the conjugation of these forms is that the 

 individuals lose their customary outline and become amoeboid prior to 



Fig. 118. Conjugation in Rhizopoda. [RHUMBLER.] 

 A, B, C. Difflugia lobostoma Duj. D. Aggregated condition of Amoeba verrucosa Ehr. 



fusion, thus showing that some change has taken place in the con- 

 sistency of the plasm. 



A great number of observations have been made among the Rhi- 

 zopoda upon so-called conjugation phenomena between similar indi- 

 viduals, the process varying in complexity from simple contiguity to 

 the more complicated fusion of cell-bodies. While many of the 

 earlier observations probably dealt with division phases rather than 

 with conjugating individuals, a possibility of error first pointed out by 

 Claparede and Lachmann ('56), conjugation of shelled forms has been 

 safely established through the observations of Butschli ('74), Jickeli 

 ('84), Blockmann ('88), Penard ('90), Rhumbler ('98), and others, 

 and of unshelled forms by Schultze (Gromia, '75), Holman ('86), and 

 Kiihne ('64). 



The phenomena of cytotropy, or the mutual attraction of two or 

 more cells, among the Sarcodina at least, if not in all forms, are 

 probably closely connected with conjugation and may possibly be the 



