276 Dr. Waller on some Tissues of the Animal Frame, 



ence of small filaments projecting upwards in a vertical direc- 

 tion, and which are probably the ciliary filaments with which 

 they are studded. 



The flattened appearance of the epithelial scales, I believe, 

 is owing to the manner in which the light is transmitted 

 through the membrane, which gives a view of their horizontal 

 section, but conveys no idea of their projection upwards. I 

 am led to this conclusion from the appearance of the papillae 

 and glands, which project upwards into the mucous mem- 

 brane, and are found to present at their borders several pro- 

 jections, such as we should expect from small bodies shaped 

 like those figured by Henle, as existing on the inner side of 

 the cheek in man. In Plate I. figs. 1 and 2, may be seen 

 these toothed projections corresponding in size to the scales, 

 which corroborates the view of regarding each of them as 

 forming a small conical projection above the membranes. 

 The scales on the under surface are much smaller and more 

 indistinct, but are the same in other respects. 



Cilia and ciliary movements. — These may be seen with great 

 facility at the upper surface, when a sharp border of the 

 tongue is examined under strong magnifying power. For 

 this purpose a portion of the tongue is to be placed between 

 two slips of glass with a little water : the foreign particles in 

 suspension will then show by their agitation the existence of 

 the ciliary motion, which will be seen at the borders of the 

 membrane. There will be perceived, under favourable cir- 

 cumstances, minute projections or filaments; but more fre- 

 quently there will be seen merely a kind of flittering move- 

 ment, without the cilia which give rise to it being distinguished 

 separately. These cilia were not included in the communica- 

 tion to the Societe Philomatique, and their detection is due to 

 M. Donne at a subsequent period. 



Tongue of the Toad. — It is covered with more irregular 

 epithelia, generally not so large as those of the Frog ; in other 

 respects they are much alike. 



Tongue of the Lizard. — It is very remarkable for the thick 

 and horny papillae with which it is covered. These are all 

 protected by a covering which is much like the epidermis. 

 The layer of papillae presents no appearance of circulation on 

 the surface, and is too opake to allow any passage of light; 

 but when the tongue is retained out of the mouth I have often 

 observed the circulation at the borders ; and the globules of 

 blood are sufficiently voluminous to be easily seen by the 

 simple microscope. 



Papilla?, Glands, fyc.— On the frog's tongue, immediately 

 beneath the layer of epithelian scales, are seen various small 



