300 



GRIFFIN. 



. The feature of most interest in regard to the cirri is the ease with wliich 

 the individual cilia of which they are composed may be demonstrated. 

 After the Euplotes have been confined for only a few minutes under a 

 cover-glass, the tips of the ciiTi become frayed, and a little later the 

 entire cirrus has changed to a brush of strong cilia which may either beat 

 as a nnit, or each cilium may move independently. 



All reagents cause the cirri to, break more or less into their ciliary 

 elements, while a change in the density of the water will cause them to 



brush instantly and most markedly 

 of all, though the animal may still 

 lie alive. Each of these cilia is 

 connected with a basal granule. 

 (Text figure 8; Plate III, figure 

 '8.) The basal granules lie in a 

 plate of specially dense and stain- 

 able, nongranular ectosarc. (Plate 

 III, figure 8.) 



On examining tangential sections 

 of the ventral surface of the body, 

 it was found that the basal gi'anules 

 of each cirrus are arranged in 

 several parallel rows (text fignire 

 8), the rows being slightly oblique 

 to the axis of the body. That the 

 cirri are composed of bundles of 

 fused cilia has been believed for 

 many years. This last observation 

 indicates, in addition, that each 

 cirrus has developed, not from a single low, but from several of the rows 

 of cilia which we may imagine to hkve covered the body of the ancestral 

 form. It has been difficult to reconcile this theory with the observations 

 of Stein and St3rki that the new cirri of Styloniehia arise from portions 



of a delicate undulating membrane. 

 My own observations of the develop- 

 ment of cirri in Euplotes worcesteri 

 lead me to believe that this objection 

 is not serious. (See Part II.) In 

 addition "Wallengren observed that in 

 Euplotes harpa and Styloniehia the 

 ^^ ., ^ ^^ . . rudiments of the cirri appear sepa- 



FiG. 9. — Contractile fibrils ot the cirri, '■ '■ '- 



drawn from an unstained specimen ratei}''. 



fixed in corrosiye-fornaol-acetic. (ol- j^^ connection with the baseS of the 



lowed by alcohol. 



cirri are certain .endoplasmic fibers. 

 (Plate II, figure 4; test figure 9; Plate III, figure 8.) A fiber passes 

 forward from the base of each anal cirnis, the five fibers gradually 



Fig. S. — Camera lucida sketcli of a tan- 

 gential section of the ventral surface, 

 showing the rows of basal granules and 

 some of the contractile fibrils of the cirri. 



