632 



CILIA. 



in the mouth and pharynx. It was also sought 

 for unsuccessfully in the lachrymal passages. 



The authors mentioned have now examined 

 it in twelve species of Mammalia, and have 

 found the same appearance in all of them ; 

 they add that, although they have had no op- 

 portunity of inspecting the parts in the human 

 body so soon after death as to see the cilia in 

 motion, yet by covering the surfaces to be 

 examined with blood, which preserves the ap- 

 pearance longer than any other fluid, they 

 were able on examination, thirty hours after 

 death, satisfactorily to distinguish the cilia 

 both in the nose and windpipe. 



I have seen the phenomena in the nose, 

 trachea, and Fallopian tubes of the Rabbit, and 

 in the trachea of the Dog.* 



According to Purkinje and Valentin the 

 motion occurs in the uterine mucous mem- 

 brane, both in the impregnated and unimpreg- 

 nated state; but in gravid animals it appears 

 only on those parts of the uterus which are 

 not adherent to the chorion or external enve- 

 lope of the foetus. The direction of the impul- 

 sion they state to be from the internal ex- 

 tremity of the tube, towards the orifice of the 

 vagina. It seems wanting on the genital mem- 

 brane of young animals. On the other hand, 

 it occurs in the respiratory passages of the 

 foetus, it was detected in foetal calves and 

 lambs, and in foetal pigs not more than two 

 inches long. The authors could not with cer- 

 tainty distinguish the direction of the im- 

 pulsion in the air-passages of Mammalia. In 

 some parts of the nose of the Rabbit, I have 

 been able to trace it clearly enough by means 

 of charcoal powder, the parts being placed in 

 tepid water. On the inferior turbinated bone 

 the grains of powder were slowly carried for- 

 wards, following the direction of the project- 

 ing laminae of the bone. On breaking open 

 the maxillary sinus and trying its lining mem- 

 brane in the same way, the impulsion seemed 

 to be directed towards the back part of the 

 cavity, where its opening is situated. By the 

 same means I traced the direction in the wind- 

 pipe of a young dog a few days old ; the im- 

 pulsion was best marked on the posterior part 

 of the tube, and there it was obviously di- 

 rected towards the larynx, the direction being 

 thus different from what Purkinje and Valentin 

 observed in the domestic Fowl. 



PART ir. 



1. Summary of the animals in which the 

 ciliary motion has been discovered. 



From the foregoing facts it appears that the 

 ciliary motion is a phenomenon which prevails 

 most extensively in the animal kingdom, hav- 

 ing been found in the highest as well as the 

 lowest members of the Zoological scale. 

 Among Vertrebated Animals it has been dis- 

 covered in Mammalia, Birds, and Reptiles, 

 viz. the Batrachia, Sauria, Ophidia, and 

 Chelonia. Of the Invertebrata it has been 



found in Mollusca, viz. Gasteropoda, Conchi- 

 ., , , j rri j. A 



Jerous acephala, and lumcata ; in Annelida, 



* Edin. New Philos. Journal, xix. 



viz. Aphrodita, Arenicola, and many Tubi- 

 colur worms, also in Planar ia and Naiades; in 

 Echinodermata, viz. the Asterias and Echinus; 

 in Actiniae; in Medusae; in Polypi; in Sponges; 

 and in Infusoria. It is a remarkable fact that 

 no trace of it has been observed in Fishes. 

 I at one time supposed that the pendent 

 filaments of the gills of the foetal Skate and 

 Shark might probably be found to exhibit it ; 

 but my friend, Dr. Allen Thomson, has care- 

 fully inspected those of the Skate without 

 being able to perceive any appearance of it.* 



2. Organs or parts of the body in which the 

 ciliary motion has been ascertained to exist. 



These may be referred to four heads, viz. 

 the skin or surface of the body, the respiratory, 

 alimentary, and reproductive systems. Its use 

 in all these cases, or the function in general of 

 the cilia, is to convey fluids or other matters 

 along the surface on which the cilia are placed, 

 or, as in the Infusoria, to carry the entire 

 animal through the fluid. 



a. Surface of the body. Cilia have been 

 found on different parts of the external surface, 

 in Batrachian larvse, in Mollusca, Annelida, 

 Echinodermata, Actiniae, Medusae, Polypi, 

 and Infusoria. Their function in this situation. 

 is various ; in most cases it is evidently respi- 

 ratory, but in many instances it is also locomo- 

 tive, as in Infusoria and Medusae, or prehensile, 

 as in Infusoria and Polypi ; and perhaps it is 

 in some animals subservient to the sense of 

 touch or smelling, as may be conjectured with 

 regard to the cilia on the tentacula of some 

 Mollusca. 



b. Respiratory system. The ciliary motion 

 has been observed on the lining membrane of 

 the air-passages of Mammalia, Birds, and Rep- 

 tiles ; and there, whatever may be its other 

 uses, it at least serves to convey the secretions 

 along the membranes, together with foreign 

 matters, if any are present. It exists also on 

 the external gills of Batrachian larvae, and on 

 the gills of Mollusca and Annelida. In other 

 Annelida, in Echinodermata and Actiniae, it 

 is found on the external surface of the viscera 

 and on the parietes of the cavity containing 

 them, to which cavity the water has access. 

 The pores and canals of the Sponge are pro- 

 bably both respiratory and alimentary passages, 

 and under this head we must refer again to the 

 cilia on the external surface of Medusae, Polypi, 

 and Infusoria, as belonging partly to the respi- 

 ratory system. The use of the ciliary motion 

 on the respiratory organs of animals with 

 aquatic respiration is obviously to renew the 

 water on the respiring surface. 



c. Alimentary system. The motion occurs 

 in the mouth, throat, and gullet of Reptiles, 

 in the entire alimentary canal of Mollusca, on 



* Since the above was writ ten, a short notice 

 has appeared in " 1'Institut" of 16th December, 

 1835, of the Transactions of the Leopoldine Aca- 

 dem y for 1834-35, from which it appears that Pur- 

 kinje and Valentin have at last succeeded in d 

 in S the phenomenon in Fishes. Ihey found it in 

 the orga ^ of sme ilmg and the internal genital 

 organs of the female. No further particulars are 

 stated. 



