FOREIGN BODIES IN EGOg. 179 



The most probable explanation of these curious facts appears to me to be 

 the following: — The alimentary canal and the oviduct or tube through which 

 the eggs are passed out of the body of the fowl, both terminate in a common 

 receptacle, called the cloaca; but each time that the former rids itself of 

 foreign matter, its termination is brought by certain muscles to the exterior 

 of the body, and thus the matter is not retained within the cloaca; the 

 bird however, having swallowed the coins in the one case, and the glass in 

 the other, was unable to expel them, and they stuck in the cloaca, instead 

 of being passed out of the body altogether; when by a peculiar nervous action 

 called by physiologists, reflex, they must have entered the orifice of the 

 oviduct, and travelled up that tub^ a certain distance before the calcareous 

 envelope, or shell of the egg was formed, which thus covered them over, and 

 concealed them from view. It would be interesting to know exactly the 

 situation of foreign bodies in these cases — whether next the shell and separated 

 from the albumen or white of the egg by the memhrana putaminis, or thin 

 skin capable of being peeled off from the interior of the shell; or whether 

 embedded in the albumen — a circumstance not noted as far as I can learn 

 in either of the cases mentioned. 



This ex23lanation appears more probable from a curious case that occurred 

 in a little boy who was dragged along a gravel path by his playmates; two 

 years after, symptoms of stone in the bladder were noticed, and upon operating 

 a large stone was extracted, the nucleus or centre of which was formed by a 

 piece of gravel; several pieces of which were extracted from the urethra at 

 the time of the accident, but this one must have travelled up by reflex action 

 to the situation mentioned. 



Perhaps it may be as well to explain what reflex action of the nerves is, 

 in a homely and popular way, for the benefit of those who have not studied 

 physiology. By such is meant those actions that take place, involuntarily, 

 with or without consciousness, where irritation is applied to the nerves of one 

 part of the body, causing motion in or near the part from a nervous influence, 

 conducted along one class of nerves, called afferent or sensory, to the spine, 

 and thence reflected by another class, called effei-ent or motor: for example, a 

 person takes snuff, causing irritation of certain nervous fibrils spread out upon 

 the lining surface of the nose, of which irritation he is conscious; this is con- 

 ducted to the upper part of the spine by one class, and thence reflected by 

 another class, of nervous fibrils, to the muscles of the face and respiration, 

 generally causing sneezing. Or again, if the finger be placed in the palm of a 

 sleeping child the hand contracts, and grasps the irritating body, without any 

 consciousness on the part of the infant, through a nervous action of the same 

 character as in the previous case. Should any of your readers know of a 

 more probable explanation, they certainly would confer a favour by stating it. 



Fazeley, Staffordshire, August 2dth. 1851. 



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