AN AMICRONUCLEATE OXYTRICHA. II 



133 



ture A. Subsequently the formation of double animals has oc- 

 curred repeatedly in other cultiu'es of this amicronucleate race, 

 but all such forms coming directly from culture AT are desig- 

 nated as Twin Series 1 (p. 136). 



A thorough study was made of some of these double individ- 

 uals, which showed that they could be interpreted as two single 



Figs. 2 to 5 Photographs of a model constructed from drawings of a typical 

 double animal. Figure 2, ventrolateral view; figure 3, ventral view; figure 4, 

 lateral view; figure 5, end view (anterior). 



animals fused together along the middorsal line. As will be seen 

 fi'om the following text figures, the twins were slightly separated 

 anteriorly, but were firmly united along the dorsal side to the 

 posterior end. Figure 1 shows the usual appearance of the living 

 twin. 



