60 A PAPER ON EGGS, 



ovum, to contraction, pushes the ovum gradually onwaixls ob- 

 liquely along the '' rifling" of the lining membrane. 



By the time the ovum arrives at the narrow part of the tube 

 it is much increased in bulk by the addition of the albumen, and 

 will act as a proportionally greater stimulus to the walls of the 

 o^dduct, and will demand and receive greater muscular force to 

 enable it to overcome the resistance of this commencement of 

 the narrower part. 



Arrived in the isthmus the ovum stimulates the lining mem- 

 brane there to the performance of its function, which is the 

 exuding in successive quantities of a fluid resembling fibrin, or 

 some peculiar modification of albumen, for it solidifies, or sets, 

 by fibrillation, in much the same way as does the plastic fluid 

 wliich is given out by an inflamed serous membrane in the higher 

 animals. The membrane thus formed is that on which the shell 

 is to be laid {membra na puta minis) ; it consists of fibrils which 

 are closely felted as it were together, united every here and 

 there and arranged in two principal layers, each di^-isible into 

 otlier minor ones, superimposed upon each otlier, and forming 

 together a strong and tough covering for the ovum. The ovum 

 now has had bestowed upon it a more distinctive shape, becomes 

 rougher, and has an increased size and consistence. It has, in 

 short, taken to a great extent its future form. "Wind eggs, or 

 those prematurely laid, ha^*ing generally more or less approxi- 

 mation to the normal c^^ shape, and being white, not coloured. 



From the isthmus the membrane-covered egg is driven into 

 the more open and fleshy part of the oviduct, the tissues of which, 

 being in consequence greatly excited, prepare to execute their 

 functions ; the lining membrane pours forth an abundant flow of 

 a thickish muddy white fluid, holding in solution, in a hundred 

 parts, ninety-seven of carbonate of lime, one part of phosphate of 

 lime and magnesia, and two parts of animal matter, with traces 

 of .sulphur and iron. 



Tiiis licjuid plaster is thrown f)ut over the whole o^g, and gra- 

 dually as the egg is thrust downwartls layer after layer is exuded 

 ond set*, just as was the case with the albumen and the shell 

 membrane. In flu- fluid thus effused a verv delicato cellular 



