58 A PAPER OX EGGS, 



process, for the phenomena of the solidification unci fibrillar or- 

 ganization have not been minutely examined, nor has any dif- 

 ference yet been ascertained between the substance secreted in 

 the isthmus, which undergoes the fibrillation without calcifica- 

 tion, and that of the uterine dilatation, which seems to have no 

 such tendency, remaining amorphous or cellular, and having very 

 soon a deposit of calcareous matter formed in it. 



'* By the time the egg arrives in the uterus it has acquii'cd its 

 peculiar oval form, the small end pointing downwards in the 

 oviduct. The cause of this form, which is already apparent in 

 the white previous to the formation of the shell, is somewhat 

 obscure, on account of the complexity of the mechanical condi- 

 tions influencing the egg in its passage. It may probably depend 

 on the circumstance that the soft mass dilates the oviduct more 

 gradually as it insinuates itself between its coats, in being pro- 

 pelled onwards, whilst the part of the duct through which it has 

 passed contracts more abruptly and firmly in consequence of the 

 stimulus of distension to which it has been subjected. But the 

 variety of forms which occurs in the eggs of different birds and 

 other animals must not be forgotten, as indicating that the pecu- 

 liarity of a lesser or greater end is not essential, and may depend 

 on very slight or transient circumstances. Perhaps the greater 

 density of the albumen secreted over the end which advances 

 first in the oviduct may also have some effect in giving this part 

 the smaller volume. It certainly seems remarkable that the ends 

 of the egg should be moulded into so smooth and rounded a sur- 

 face as that of the membrane and shell by a tubular organ. 



** The egg remains a much longer time (from twelve to eigh- 

 teen or more hours) in the uterine dilatation of the oviduct 

 during tlio formation of the sliell. The mucous membrane of 

 tliis i)art differs in structure considerably from the rest. It pre- 

 sents over its whole extent large villus-likc processes or short 

 folds of a flattened form containing small follicular glands from 

 which the substance of the shell is secreted. As soon as the egg 

 enters this part of the passage a thickish white fluid is poured 

 out from the membrane which speedily coagulates on the surface 

 of the membnine lining the sliell, and very soon we can perceive 



