CHAP. II.] 



MOTIONS OF SPERMATOZOA. 



65 



Wherever the direction of the motion has been ascertained, it is 

 that which would be favourable to such a purpose. In the bron- 

 chial tubes and trachea, the direction of the motion is towards the 

 larynx, so that the cilia may be regarded as agents of expectoration. 

 In the nose of the rabbit, Dr. Sharpey observed the impulse to be 

 directed forwards, and in the maxillary sinus it appeared to pass 

 towards the back part of the cavity, where its opening is situated. 

 In the Fallopian tube, the direction is stated by Purldnje and 

 Valentin to be from the fim- 

 briated extremity towards 

 the vagina. It seems very 

 probable that ciliary motion 

 exists in the kidney, at the 

 narrow neck of each urinifer- 

 ous tube, as it passes off from 

 the capsule of the Malphigian 

 body. This has not been ac- 

 tually observed in the human 

 subject. It was discovered, 

 and has been frequently seen 

 in the frog,"* and is shewn 

 in the annexed drawing (fig. 

 3). The movement is here 

 directed towards the uri- 

 iiiferous tube, and it doubt- 

 less is destined to favour the 

 flow of the aqueous portion 

 of the secretion from the 

 capsule to the tube. 



In the inferior animals the 

 cilia seem to answer a simi- 

 lar end to that in man. 

 They exist extensively on 

 respiratory surfaces, and in 

 connexion with the genera- 



n A lc,^ 1, 

 tlVC OrgailS; and also, but 



tn n loec rl^o-ron -wn'fli +Vo 

 ) a leSS tlegiee, With, the 



organs of digestion. But in pighian capsule> m ' 

 some situations, both in man and in the inferior creatures, it is 

 difficult to determine what functions the ciliary motion can per- 

 form. Such are, in man, the ventricles of the brain ; and, in the 



* Bowman, Phil. Trans. 1842. 

 VOL. i. F 



Urmiferous tube of Frog's kidney, arising from capsule 

 of Malpighian body : a. Cavity of the tube. b. Epithelium. 

 c. Basement membrane, b'. Ciliated epithelium at the 

 neck of the tube. b". Detached ciliated particle, c. Mai- 



