1073 



CILIA. 



CIMICID^E. 



1074 



move from place to place and carry their food into their stomachs. 

 In the Polypes they are found in great numbers covering the surface 

 of the tentacula by which these animals obtain their food. Although 

 they have not been observed on the full-grown Sponges they have been 

 described by Dr. Grant as existing upon the ova of these animals 

 before they become fixed. Though not abundant in the Acaleplue, 

 they have been seen by Dr. Grant and others in the Beroe pilew and 

 other Meduitfe. Dr. Sharpey has observed them in the various forms 

 of the Echinodtrniata, and also in the A nnelida. In the Mollusca 

 they are very abundant, and one of the best means of examining these 

 organs is afforded by the common mussel. Till within a recent 

 period it was supposed that Cilia were confined to the Invertebrate 

 classes of animals, or at least the observation of their existence to any 

 extent in the Vertebrata was very limited. One of the earliest obser- 

 vations of their presence in Vertebrate animals was by Steiubuck, a 

 German anatomist, who found them upon the gills of the Salamander. 

 Within the last few years Purkinje and Valentin have devoted much 

 attention to the subject, and have found that Cilia exist very 

 generally on the moist surfaces of the membranes of all the higher 

 animals. The systems of organs on the surface of which Cilia have 

 been detected are as follows : 



1. The Surface of the Body. In this situation Cilia have been 

 detected in the Infusoria, Polypi, Medusae, A ctinia, Echinodermata, 

 and in the larvae of the Batraehian Reptiles. 



2. The Respiratory System. Cilia have been detected in the lining 

 membrane of the air-passages of reptiles, birds, and Mammalia, in the 

 gills of the larvae of the Batraehia, and on those of the Mollutca and 

 Annelida. Those on the external surface of the Infusoria, Polypes, and 

 Medusa must also be regarded as belonging to the respiratory system. 



3. Alimentary System. They are found in the mouth, throat, and 

 gullet of Reptiles, in the entire alimentary canal of Molliuca, in the 

 stomach of the A sterias, kc. 



4. Reproductive System. Ciliary movements have been observed 

 in the mucous membrane of the Fallopian tubes, in the uterus and 

 vagina of Mammalia, and in the oviduct of Birds and Reptiles. A 

 peculiar ciliary movement has been observed in the embryo of many 

 animals. This movement occurs while the embryo is in the ovum, 

 the Cilia producing a current in a certain direction along its surface, 

 or causing the whole embryo to move in an opposite direction. In 

 many instances when the embryo has escaped the egg it moves about 

 by means of Cilia in the same way as occurs in the naked gemmules 

 of the Sponge. 



There can be little doubt that the functions performed by the Cilia 

 in these various parts of the body of animals are important ; at the 

 same time their absence in a great number of cases, in organs which 

 perform the same functions as those which possess them, must lead 

 to some hesitation before pronouncing a decided opinion with regard 

 to their use. Where they are situated on the external surface of the 

 bodies of animals they seem to be the active organs of movement. 

 Where respiration is carried on by means of the external surface, an 

 in the Infusoria and Polypi/era, the Cilia assist this process by 

 removing the used water and bringing fresh currents to the surface 

 containing the matter to be oxygenated. They may undoubtedly 

 perform the same office when seated on internal respiratory mem- 

 branes. On the surface of the reproductive organs of the higher 

 animals they may also assist in bringing the unimpregnated ovum in 

 contact with the fertilising cells of the male fluid. The movement 

 in the embryo has probably the same object in view as that on the 

 respiratory membranes, the bringing the surface in contact with 

 currents of oxygenated water. 



In coming to the conclusion that the motions of fluids on the 

 surfaces of membranes are produced by Cilia where these organs exist, 

 Dr. Sharpey observes, " The currents cease when the motion of the 

 cilia stops, they are strong and rapid when it is brisk, and feeble 

 when it languishes ; and though there are modifying circumstances 

 or perhaps exceptions, yet in general the magnitude and velocity of 

 the current seem to be proportioned to the size and activity of the 

 cilia. It is true that while doubts remained as to the existence of 

 cilia in several well-marked instances where the water unequivocally 

 received ite motion from the surface over which it flowed, and inde- 

 pendently of any visible contractions of the animal tissue, there was 

 always considerable room to doubt, whether, even in the cases where 

 cilia were manifest, the effect of these organs was wholly mechanical, 

 and whether the motion of the water was not rather due to some 

 peculiar impulsive power in the tissue differing from mechanical 

 action. But more extended observation has almost wholly removed 

 these exceptions, while it has considerably increased the number of 

 conforming instances, insomuch that there seems at present no 

 necessity for having recourse to any other explanation of the motion 

 of the fluids than that it is produced by the action of the cilia, and 

 that their action is the result of muscular contractility, a known 

 property of animal tissues." 



There are however some remarkable exceptional cages. Currents 

 are observed in the Sponge, in the stem and branches of the 

 flertularuc, but no Cilia. There are also a number of remarkable 

 cases of the movements of fluids in cells in the vegetable kingdom, 

 which cannot be ascribed to the existence of Cilia, as those seen in 

 the cells of Chara, Valitneria, the hairs of Tradetcantia, Ac. 

 HiT. HIST. DIV. YOL. I. 



When first discovered the Cilia were supposed to be confined to the 

 organs of animal bodies. In 1843 Meyer and Thuret announced that 

 they had discovered Cilia on the spores of several species of Confen-ce. 

 They were subsequently discovered on the surface of several species 

 of unicellular plants, as also on the spermatozoids, which occur in 

 the Ferns and many of the lower forms of Crypt 'ogamia. 



For further information consult the article ' Cilia,' by Dr. Sharpey, 

 in the ' Cyclopaedia of Anatomy and Physiology,' to which we are 

 much indebted in drawing up this article ; also the paper of Purkinje 

 and Valentin, entitled ' Commeutatio Phyaiologica de Pheenomeno 

 Motus Vibratorii continui,' &c., translated in the ' Dublin Journal of 

 Medical and Chemical Science' for May, 1835, and in 'Edinburgh 

 Kew Philosophical Journal," vol. xix. ; also ' On Unicellular Plants 

 and Animals," ' Microscopical Journal," vol. i. 



CILIATA. [MOTELLA.J 



CILIC^EA. [ISOPODA.J 



CILIOGRADA. [ACALEPHJS.] 



CIMBEX, a genus of Hymenopterous Insects of the section 

 Terebrantia, sub-section Securifera, and family Tmthndinidce. 



The genus Cimbex, as it formerly stood, has been subdivided 

 (principally by Dr. Leach) into the following sub-genera : Cimbex, 

 Perga, Syzygonia, Trickiosoma, Clavellaria, Zarea, Abia, and Amasis. 

 All these sub-genera have the antennas short, and terminated by 

 thickened joints, which are nearly of an oval form ; the third joint 

 of the antennae is long, forming a knob : the superior wings have 

 two marginal and three sub-marginal cells. 



The antennae of these insects generally present six distinct joints, 

 of which the two basal joints are very short, and almost concealed 

 by the hair on the head ; the third ia long, the fourth and fifth are 

 of moderate length, and the sixth is elongate (or moderate), rounded 

 at the apex, and tapers more or less towards the base ; this last joint 

 is, however, evidently composed of two or three joints consolidated. 

 All the joints of the tarai have a membranous pad attached to their 

 under side, and protruding from their apex. 



The genus Cimbex, as now restricted, may be known by the 

 following characters : Body slightly hairy ; abdomen with the basal 

 segment emarginate above (that is, it appears as if a semicircular piece 

 had been removed); the space thus left unprotected by the horny 

 covering filled up with a membrane. Thighs of the four posterior legs 

 of the males very thick, those of the females moderate. Tarai 

 of the males with a tooth-like projection on the under side of the 

 basal segment. 



This genus includes the largest species of the family Tenthredinidrr. 



C. Griffinii is about an inch in length, and when the wings are 

 expanded its width is about one inch and three quarters. It is of a 

 reddish-brown colour; the abdomen is yellow, and more or less 

 clouded with brown towards the base; the antennas and tarsi are 

 yellow, the former is brighter towards the apex. 



The larva, we have been informed, feeds upon the sallow, and is 

 not uncommon in the neighbourhood of Cambridge. Mr. Stephens 

 enumerates eight British species of this genus, some of which how- 

 ever, it ia thought, will eventually prove to be mere varieties 



CIMEX. [Boo; CimciDX.] 



CIMI'CID^E, a family of Hemipterous Insects, the species of 

 which may be distinguished by their having the rostrum short, and 

 consisting of two or 

 three joints only ; the 

 labrum also short, and 

 without stria; ; the eyes 

 are moderate ; the body 

 is generally very much 

 depressed. The prin- 

 cipal genera are Cimex, 

 Aneurus, Aradia, A gram- 

 ma, Tingit, and Uictyo- 

 nota, all of which are 

 found in England. The 

 ?enus Cimex ia distin- 

 juished principally by 

 the extreme slenderness 

 of the two terminal 

 joints of the antennae, 

 which are not thicker 

 than a hair. The body 

 ia very much depressed : 

 the thorax is transverse ; 

 antennae 4-jointed ; basal 

 joint very short, second 

 long, the third of about 

 equal length, the fourth 

 rather shorter. Labrum 



rather long, somewhat i. B ed-Bug (' fectefarftw) magnified . 



pointed, and, when the 2> natural !eng j h of the 



proboscis 18 not m use, Bame> highly magnified ; a, the l 



recurved under the head ; proboscis ; c, base of the antennie. 



proboscis 3-jointed, and, 



when at rent, lies along the under side of the thorax, its apex beiii" 



between the two fore legs at their base, 



3 Z 



head of the 

 the labrum b tho 



