No. 646] SHORTER ARTICLES AND DISCUSSION 469 



each after conjugation with the other. The following diagrams 

 may serve to make my meaning clear. 



A B. C. 



Ill em;'li figure the circles at tlio top rei)re^ent the Difflugia 



diameter of 2<) units founded a line a an<l then was i>aiivd with 

 a I)iffluu-ia with 4 si)ines with a diameter r>f IVA. Tliis lia<l i)r<;vi- 

 ou^lv started line cL Ahov the separation of the Difflugias. 

 th'ey founded lines b and c re^'ectively. The doited cross lines 

 represent the influence which might be expected to come from 

 the other member of tlie pair if there were actual conjugation. 

 Line a was carried on until 108 individuals were produced, the 

 average number of spines being 2.79 and the diameter 29.6 

 units. Line b, started after tlie attachment of the progenitor 

 to the other Oifflnuia. was carried for 107 individuals, with an 



and number of spines of the ■ . • mi of the 



line started by each before tin • t.,r <'X- 



ample, line b should be more likf i - : ^ ; and line 



c should be more like a than is Vuu- ,1. and >>n ,,u throughout 

 the experiments. 



