4 INNERVAT10N. [CHAP. XVI. 



and contain usually two nucleoli, even more pellucid than them- 

 selves. The surrounding substance is in relatively small quantity, 

 and is seen either as a mere film around the nucleus, or vertically 

 elongated in various degrees. In the superficial series, a, the nu- 

 clei, though lying on the same general level, are placed some higher 

 and some lower, as if for convenience of package, since the parti- 

 cles bulge where the nuclei are situated. The nuclei are scarcely 



Fig. 103. 



View of the ciliated epithelium of the nose, seen in section : a. Superficial series, clothed with 

 cilia, b. Deeper series, becoming elongated vertically, c. Various shapes of the perfect ciliated 

 particles. Magnified 180 diameters. 



different in size or shape from those below. The surrounding 

 granular substance of the particle is, however, much longer than 

 before; below, where it is implanted between the particles of the 

 deep series, it is pointed, though sometimes blunt, and often club- 

 shaped, while the upper end enlarges, and terminates by a flat sur- 

 face, from which the cilia project, c. It must be observed, that 

 the cell-membrane, so apparent in the scaly epithelium heretofore 

 described, is not to be found in this variety. It is either early ab- 

 sorbed, or else so delicate and so united to the contained substance 

 as not to be distinguishable as a separate object. 



It appears clear that this double series of particles constitutes two 

 stages of growth of the same structure. Instances are not wanting of 

 particles intermediate between the two, in which the future surface 

 of the membrane is marked by a horizontal line, above which the 

 granular substance exhibits a vertically fibrous structure, indicative 

 of the coming cilia. Moreover, we have met with examples in 

 which a surface perfectly ciliated was still covered with a layer of 

 other ciliated particles, that, from their half-dissolved appearance, 

 had evidently passed their prime, and were in process of decay. This 

 progressive development of the particles as they recede from the 

 vascular source of their nutriment, and especially the evolution at 

 last of those delicate evidences of life, the ciliary appendages, is a 

 glaring example of the essential independence of the vitality of the 

 tissues on the blood-vessels, and makes it more easy to conceive the 

 really subordinate or ministerial office of those channels. 



