10 NERVOUS SYSTEM AND SENSE ORGANS 



of the body. The basal granules of cilia, cirri, and membranelles 

 are considered as secondary rather than primary structures. In 

 ciliates the connection between neuromotor apparatus and cilia is 

 not clearly established, but there is some indication that there may 

 be connection. 



In many flagellate protozoans the flagellum has been described 

 as springing from a center or blepharoplast. A very primitive type 

 of neuromotor apparatus is described by Wilson, 1916. The flagel- 

 lum arises from a blepharoplast which grows out from the central 

 karyosome (Fig. 2, A-D). The blepharoplast is connected with 

 the karyosome by a rhizoplast. 



In other forms the blepharoplast may be composed of one or 

 more granules which may or may not be connected with the nucleus. 

 The basal granule of the flagellum may have a double function of 

 being a basal granule of the flagellum and also a division center for 

 the cell. In some forms the two functions are separated in two 

 granules. In some a number of granules surround the blepharo- 

 plast or may be derived from it. These migrate backwards and 

 come to form the ])arabasal lx)dy which may in some cases be at- 

 tached by a number of fibrils to the blepharoplast. This parabasal 

 body is interjn'eted as an acces.sory kinetic reservoir. A further 

 elaboration of this structure is the chromatic rod of some species. 



Various types of flagellates with their internal connections are 

 shown in Fig. 3. One of the most complex conditions we find in 

 Ginrdia, Kofoid and Christianson, 1915. This is a binucleate organ- 

 ism equivalent to two flagellates, each containing one nucleus and 

 one blepharopla.st at the end of a single axostyle, three flagella and 

 a half or whole axostyle, depending upon the stage of the organism. 

 Two blepharopiasts are connected by cross commissures and are 

 anterior. The lateral flagella cross the middle line. The blepharo- 

 piasts are joined to the nuclei by rhizoplasts and also to the para- 

 basal body lying along the axostyle. "Each organism has its own 

 neuromotor apparatus, but due to the crossing of the fibers between 

 the blei)haroplasts the two organisms are unified. (Fig. 2, M.) 



According to Yocum and others the motorium of ciliates is 

 homologous with the blepharopla.st of flagellates. According to 

 Dobell the blepharoplast of the jirotozoan is homologous with the 

 end knob and the axial filament of the metazDan sperm, whose func- 

 tion is to provide for the locomotoror activities of the cell. The.se 

 structures are akso homologous with the centrosome of resting cells. 



It seems probable that other strands and coordinating centers 

 may be found in protzoans in addition to those already described. 

 This tyi)e of .system for control or coordination is not in any sense 

 homologous with that of Metozoa and in no .sen.se does it lead to 

 flevel()|)meiit of the nervous .system of more comi)iex forms. From 

 what has already been .said it is probable that methods of coordina- 

 tion are not at all alike in Protozoa and Metazoa; in fact it may well 



