6 Dr. Paris on the Physiology of the Egg. [July, 



lower portion of the uterus, and in this operation we recognise a 

 process which, at the same time, answers two of the most import- 

 ant purposes of the animal ; it at once serves the individual, and 

 contributes to the perpetuation of the species ; for while it 

 removes the superabundant calcareous matter, which, if allowed 

 to accumulate, must render the bird incapable of flight, and 

 defeat the best purposes of its existence, it furnishes the germ 

 of the future animal with a strong and convenient defence. It 

 sometimes happens that the eggs of birds are deposited without 

 the shell ; this may arise from the secretion of calcareous matter 

 not keeping pace with the too exuberant production of the yelks, 

 a circumstance which may depend upon a variety of causes ; but 

 as it is not my intention to discuss the question of the origin of 

 lime in animal bodies, I shall, upon the present occasion, rest 

 satisfied with recording some facts connected with the subject. 

 The experiments of Vauquelin, which prove that the quantity of 

 calcareous matter voided by the system exceeds that taken in 

 with the food, suggested to Fordyce that birds must require 

 calcareous matter during their laying, and that if the animal 

 were deprived of this earth, the shell would never be formed. 

 From observations made by myself, I am inclined to reject this 

 theory ; for birds occasionally deposit eggs without shells, who 

 have free access to lime ; and, on the other hand, although they 

 be carefully kept from lime, they will nevertheless produce 

 calcareous secretions. 



As far as the light of analogy extends, it would seem that 

 lime is a product of animalisation, and that its secretion requires 

 a considerable energy of constitution ; this is rendered probable 

 by the well-known phenomena of rachitis; the absence of the 

 shell, therefore, depends probably upon some constitutional 

 cause in the bird, and not upon the privation of lime. 



During my experiments, many years since, a curious circum- 

 stance occurred to a hen that was kept for the purpose that 

 deserves to be placed upon record. This bird had broken its 

 leg, and the limb was carefully bandaged, when, after a few 

 days, several eggs destitute of shells were found upon the pre- 

 mises, which I ascertained had been produced by the bird in 

 question. Now it may be fairly asked whether, in this case, the 

 calcareous matter designed for the formation of the shell was 

 not employed in the regeneration of bone ? In the human 

 species, the converse of this takes place ; for a fracture, occur- 

 ring during pregnancy, frequently does not unite until after 

 delivery.* Here then nature evinces a greater anxiety for the 

 offspring than for the parent ; while, on the contrary, the fecun- 

 dity of an oviparous animal would seem to render such a precau- 

 tion unnecessary. The same law will explain why women who 



* In the fourth volume of Medical Observations and Inquiries, a case is communi- 

 cated by Dr. William Hunter from Mr. Alanson, Surgeon at Liverpool, of a simple 

 fracture of the tibia in a pregnant woman, where the callus was not formed until after 

 delivery. The accident happened during the second month of her pregnancy, and until 

 her delivery no adhesion had taken place; but in the course of nine weeks afterwards 



