BY D. EMBLETOIST, M.I). 59 



with the microscope small heaps or united groups of particles 

 somewhat of a crystalline appearance, but in reality calcified 

 blastema, studded over the whole surface. These are the cal- 

 careous particles of the shell which are deposited in a delicate 

 matrix of animal tissue of a large cellular structure. The deposit 

 goes on rapidly increasing : at first the shell is soft, it remains 

 friable for a considerable time, and subsequently it gradually 

 acquires its peculiar dry hardness. 



" The egg remains in the uterine dilatation till it is about to 

 be laid. The expulsion of it from this cavity, through the nar- 

 row part of the tube leading to the cloaca, requires very strong 

 muscular contraction for its accomplishment ; and although the 

 egg always descends in the oviduct, and usually lies in the uterus, 

 with its narrow end downwards, both Purkinje and Yon Baer 

 state that they have sometimes seen its position inverted towards 

 the end of the time of its residence there, in consequence of the 

 force of the muscular contractions of the wall of the oviduct." 



Dr. Thomson also states that "during the passage of the egg 

 and the formation of the albumen, membrane, and shell, a greatly 

 increased determination of blood is observed in the vessels of the 

 several parts of the oviduct," and that ''the advancing motion 

 of the egg of the fowl is caused by the peristaltic action of the 

 muscular coat of the oviduct, which may easily be seen in any 

 laying fowl opened immediately after death." 



On opening a female bird killed during the laying season, it is 

 remarkable how large a space in the abdomen is occupied by the 

 ovarium and oviduct, especially if an egg be on its passage, and 

 how large, vascular, and red these organs are as compared with 

 the intestine. 



They have been in full functional activity, their sensibility 

 and other vital i)roperties intensified by the influences of tlie 

 male bird. 



The ovum, entering the upper end of the oviduct, acts on the 

 latter as an additional stimulus, the consequence of which is, that 

 the lining membrane pours out a succession of secretions of albu- 

 men, and the muscular tunic stimulated through the nerves of 

 the visceral system, and by the actual preseuce or contact of the 



