328 GENERAL ORNITHOLOGY part n 



yelk, it is still morphologically a simple cell, affording the maximum 

 dimension of any known protozoan or single-celled animal. Enter- 

 ing the oviduct, the germ-yelk part of the whole mass is fertilised 

 by spermatozoa, unless this process has before occurred in the ovary, 

 and in its passage through that tube the yelk-ball becomes invested 

 successively with the mass of transparent albumen known as the 

 " white " of the egg, and finally by the chalk shell — both secreted 

 by the mucous membrane lining the oviduct. 



During its functional activity, the left oviduct (there being 

 usually only this one) becomes highly developed, both as to its 

 muscular walls, which by their contractility embrace the ovum 

 closely and squeeze it along, and as to its mucous secretory surface. 

 It is supported by peritoneal folds forming a mesometry, like the 

 mesentery of the intestines ; its whole structiure and office are quite 

 like those of a length of intestine. The upper end of the singularly 

 serpentine oviduct is dilated into an infundibulum, or funnel-like 

 mouth, corresponding to the fimbriated extremity of the mammalian 

 Fallopian tube, and constituting a morsus diaboli, or " devil's grip," 

 which gets hold of the ovum to drag it down to the common lot of 

 mortals from its high ovarian birth. The infundibulum receives 

 from the mesentery a delicate tunic of unstriped muscular fibres, 

 which are so disposed as to dilate that orifice for the reception of 

 the ovum ; and during the venereal orgasm the mouth of the tube 

 is supposed to seize upon the ripest egg. The actual anatomy of 

 the arrangement, and the whole operation, is strangely suggestive 

 of one of the oldest myths respecting the serpent which bore the 

 egg of the world in its jaws. The mucous lining of the oviduct 

 consists of a layer of ciliated epithelium ; the membrane has a 

 different character in successive portions of its extent. Above, 

 when the tube is not distended with its burthen, the lining is 

 thrown into lengthwise folds, which lower down become spirally 

 disposed, and then longitudinal again before they cease. This 

 rugous portion of the tube is beset with mucous follicles, which 

 secrete "the white." The oviduct, after contracting at a point 

 called the isthmus, enlarges to a calibre sufficient to accommodate 

 the egg in its shell ; for this is the shell-forming part, homologous 

 with the mammalian uterus (a sinister semi-uterus at least), lined 

 with large villi, and beset with the follicles whose secretions calcify 



escaping from the Graafian follicle, is said to be from -^i^; to xhs of ^^ ™<'^ ^" 

 diameter. Taking it at -j^-j-, there would be 40,000 in a square inch, and in a cubic 

 inch 8,000,000. The largest bird's egg known, that of the JEpyomis, is said to have 

 a content of about a gross of hen's eggs — 144. Supposing the yelk of the ^pyornis 

 egg to bear the usual proportion to the other contents of the shell, and allowing for 

 the difference in bulk between a sphere and a cube of equal diameters, there would 

 still be somewhere about a billion human eggs in one ^pyornis egg-yelk — roundly, a 

 mass of them equal to that of the germs of more than one-half of the present popula- 

 tion of the globe. 



