368 STEUCTUEAL DirFEEENTIATION OF THE PEOTOZOA. 



have made longitudinal sections of the same region. In these 

 there appear, stretching across the denser band, refractive stripes 

 which terminate externally in successive fans of cilia seen edge- 

 wise, while internally these ciliary roots, so to speak, are related 

 to a remarkable series of protoplasmic bodies terminating inte- 

 riorly in the general network (fig. 7). 



I have diagrammatically represented the relations of all these 

 structures (fig. 9). It will be seen that the rods h (fig. 7) are 

 the longitudinal expression of the fine striae seen passing inwards 

 from the fan of cilia (fig. 6, V), and stand as a means of connexion 

 between the inner network and the bases of the cilia themselves. 

 Whatever their function, I have now observed them in the living 

 animal, and they appear to be permanently related to the ciliary 

 apparatus. 



EXPLANATION OF PLATE XXVII. 



Fig. 1. Spirostomum, showing the relation of the oral furrow, FO, 



2. Section showing protoplasmic network. 



3. The same, showing refractive bodies between the spaces. 



4. Section through mouth. 



5. Section with food-matter recently ingested. 



6. Cross section of oral furrow. 



7. Longitudinal section of oral furrow. 



8. Section showing the relation of the outer layers. 



9. Diagram of the oral cilia and their related parts. 



a. Dense rods in ciliary layer. 



b. Protoplasmic bodies beneath the ciliary apparatus of pharynx.- 



c. Dense outer layer of inner protoplasm. 

 c.v. Contractile vacuole. 



n. Nucleus. 

 /. Food-masses. 



