Ryder.] ■^^^ [April 21, 



tl>e egg and to be clo«e(l in front and behind it. in a longitudinal section 

 of the egg in place in tlie oviduct, we should obtain a diagram* somewhat 

 liiie tiie foregoing. The major axis of tlie egg coincides with x, which pro- 

 duced is also coincident with the closed lumen of the oviduct. Tlie minor 

 axis ?/ is transverse to the oviduct. If it is sought to move the egg within 

 the oviduct, dilated as it is, at the point where the egg lies, a certain pro- 

 pulsive force must be developed annularly by the circular fibres in the 

 wall of the duct. This requires that the force exerted from x' to y shall 

 be greater than that exerted from x to y, else the egg will not be moved 

 along X in the direction of e. This implies that the annular muscular coat 

 in the wall of the oviduct shall contrrict with greater energy from x' to 

 p tlian from x to y, but as a matter of fact tiie egg is not elliptical so that 

 the major axis x is cut into unequal parts, x' o and o x by the axis ?/. 

 Since tliis true, if the annular muscular coat of Oo be of the same thick- 

 ness tiiroughout its length by the verj^ conditions which now obtain in 

 respect of the statical equilibrium of the figure of the egg, it would, upon 

 the simultaneous contraction of those parts of the wall of the oviduct in 

 contact with it, be impelled down the latter, or in the direction of e. We 

 stated above, however, that so long as the egg contents were not confined 

 to a rigid envelope and wei'e at rest within the duct that the figure of 

 equilibrium would be an elliptical one through the long axis x of the 

 mass. Now this is just what does not happen and we can only seek tlie 

 cause for such a departure from the elliptical figure in the added propel- 

 ling force which must be applied at one side of y in order that the mass 

 may be moved at all. If the fluid mass is not rigid the very application 

 of the greater force on one side of y will cause the elliptical figure of the 

 longitudinal section of the mass at rest to pass into an ovoidal one the in- 

 stant the mass is put into motion. This simple statement of the facts as 

 to the conditions which obtain will make it self-evident that the force 

 which causes an egg to become ovoidal within the oviduct is developed as 

 a differential of force manifested between two immediately adjacent an- 

 nular segments of the duct and on opposite sides of y. 



The geometrical demonstration of this fact is so simple that it will pre- 

 sent no difficulty to any one familiar with the rules of elementary geometry. 

 If two lines a' a and b' b be drawn parallel to x through ?/, so as to toucli 

 at either end the outline of the semicircumference of the egg and ordi- 

 nates be then erected, as ac' and b c' and a' c" and b' c", four rectangles 

 will be formed which will completely exhibit the quantitative antagonism 

 of the forces developed symmetriciilly upon either side of y or of x. The 

 two rectangles, a' d' c" o and b' d" c" o are greater in area than the rec- 

 tangles a d' c' and b d" c' o on the other side of y. Tlie sum of the 

 diagonals a' o and b' o of the first pair to the left is greater than that of 

 a. and b o oi the second pair to the right of y, therefore the sum of the 

 former as representing the propelling energy developed by the pressure 



'This diagram has been constructed from the outline of a hen's egg very carefully 

 I)lotted. It therefore represents an actual contour. 



