xi PRACTICAL DIRECTIONS 549 



masculinus into the urinogenital canal, just at the anterior edge of a 

 cushion -like fold. 



B. In the female. The wide urinogenital canal with its vascular 

 walls. 



Sketch the entire dissection. 



Make a median longitudinal incision through the urinogenital canal, 

 and continue it forwards until the cavity of the bladder is exposed : slit 

 open the vagina and one of the uteri and Fallopian tubes in the same 

 way. Note and indicate on your sketch the openings of the ureters into 

 the bladder, the connection of the neck of the bladder with the urino- 

 genital canal, the large aperture in the latter leading into the vagina, 

 and the thick-lipped aperture (ps uteri), communicating between the 

 vagina and thick-walled uterus, between which and its fellow is a vesti- 

 gial septum, indicating the primarily paired character of the vagina. 

 Insert a seeker in the ccelomic aperture of the Fallopian tube. If the 

 uteri contains embryos they present a series of swellings ; cut each 

 swelling open from the ventral side, and note the foetus attached to a 

 discoid placenta (p. 541) ; remove each fcetus, together with its placenta, 

 and preserve it in corrosive sublimate (p. 135). Microscopic sections of 

 the ovary should be examined, and the hollow ovisacs noted, each 

 consisting oifollicular cells enclosing a minute ovum. 



With a scalpel or razor cut across one of the kidneys through the 

 hilus, parallel to the dorsal and ventral faces of the organ, and note the 

 pelvis , and its prolongations the calices, the urinary pyramid, and the 

 cortical and medullary portions. Sketch. Examine also microscopic 

 preparations of injected and uninjected kidney (compare p. 146 and 537). 



X. Dissect out the lumbo-sacral plexus in the pelvic cavity (p. 532), and 

 then cut through the body just behind the diaphragm ; the abdomen 

 will be no longer required, but you should retain one of the hind-limbs 

 if you wish to examine any of its muscles and joints (compare p. 64). 



E. Dissection of the thorax and neck. 



I. Dissect away the pectoral muscles, cut through all the vertebral 

 ribs of the left side, except the last five, at about a quarter of an inch 

 from their junction with the sternal ribs : from the posterior end of the 

 incision thus made, cut downwards (i.e., towards the sternum) for about 

 an inch, and then forwards, through the sternal ribs. Turn forward 

 the flap thus separated and carefully dissect it away from the underlying 

 tissues at the anterior end, so as to detach it altogether without injuring 



