Emdencc from Proto-oavs 37^5 



origin of tlie organ. In otlicr words, the (jucstion is, arc wv 

 going to reject tlie })ositive evidence \vc actiiallv liaxc. in 

 the interest of a ])urc speculation? Kveu should fuitlur 

 study find that, contrary to Patton's ohsi r\ atioiis, tluic is 

 a granule at the base of the flagellum of livrjutoinoiuts 

 lijgaei which gives rise to an axial con, the observation that 

 the achromatic su})stance of the cell participates in tlie 

 formation of the flagelhun would ikjI be set aside tlienbv. 



((I) Various Organs of Sfn/lom/cJiia and Paramcchim 



In the chapter on tlie anatomy of the proto/oa we took 

 Stylonychia as an example of the high degree of specialization 

 and integration which the sensory-locomotor system may reach 

 in a one-celled animal. While the ontoaenv of this ircniis has not 

 been studied as fully as is desirable, yet the combined knowledge 

 we have of its structure and regeneration is sufficient to Ic.-ive 

 no room for doubt that the ect()i)lasm and the outer strata of 

 endoplasm take an active part in producing the elaborate sensory 

 and motor organs. For example, the basal fibers {h. /".. figure (i ) 

 are shown by JNIaier to be attached to the basal edge of the 

 membranellae and to run inward in the endoplasm, wlnre tlu^y 

 gradually taper to very fine endings not connected with eitlur 

 the macronucleus or micronuclei or granules of any kind. 'I'he 

 inference seems unescapable that ontegenetically at least they 

 arise in the ectoplasm and grow inward. Again, as to the ecto- 

 plasm itself, Maier points out that in some j)arts of the animal 

 this is laid off into definite areas, each one of which is deeply 

 cupped outwardly and bears a cilium witii its basil granule at 

 its center. This disposition is specially clear in Paramecium 

 caiidaium. To sup])ose that such a differentiation of the ecto- 

 plasm is due to the "influence" of the basal granule, the ecto|)lasm 

 itself being passively moulded, would be so gratuitous that 

 probably no biologist would be bold enough to make it definitely; 

 yet exactly that assumi)tion would be necessary were "form- 

 determination" to be denied to everything hut chrom.itin. 



Only one other developmental point can he noticed in connec- 

 tion with Stylonijchia, that concerning the i)ro(hiction of the un- 

 dulating membrane (m b p., figure ()). That this organ be- 

 longs to the ectoplasm is generally recognized, and the considcra- 



