PEESERVATIOX OF THE HEART IX ALCOHOL. 321 



periplierad of the ligatures, and tlius complete the separation of the 

 heart from the lungs. 



§ 838. Preservation of the Heart in Alcohol. — For the study 

 of the cardiac cavities, the heart should not only be hardened in 

 alcoliol, but distended there\vitli. 



Instruments and Materials. — Coarse scissors ; coarse forceps ; sharp tracer or syringo- 

 tome ; four tlireads for ligatures, or two threads and two small compressors; syringe with 

 canula adapted to the aorta and postcava (a rubber bulb syringe Is most convenient in some 

 respects) ; small jar or glass box ; 9o per cent, alcohol, about 250 cc. ; cotton ; small pins ; 

 thread. 



At tlie the time of first preparing a heart by the injection of strong alcohol into the 

 cavities, we were unaware that it was recommended by Hyrtl and Mojsisovics (A, 58). 

 The former ascribes (A, 305) the original idea to Wm. Hunter. 



§ 839. Bemoval of the Pericardium.— In most cases this should 

 be partly removed. Pinch it up at a i oint about one third of the 

 distance from the base of the ventricles to the apex and make a 

 transverse incision. Continue this incision around the heart so as 

 to remove the apical two thirds of the pericardium. It may be pre- 

 served for reference. 



§ 840. Removal of the Blood. — The little blood that may remain 

 in the left side of the heart can be easily expelled through the aorta. 

 The right cavities usually contain considerable blood. Remove the 

 ligatures upon the postcava by carefully pushing entad of it the 

 point of the sharp tracer or the syringotome. If it has been tied very 

 tightly, it may be necessary to cut off the end of the vessel. 



Introduce the nozzle of the syringe into the postcava and inject 

 water carefully ; then manipulate the right auricle and ventricle at 

 the same time so as to expel the blood through the postcava. 



§ 841. Tying the Vessels. — Tie firmly the A. bracMo-cephalica 

 and the A. suhclavia sinistra at about 1 cm. from their respective 

 origins from the arcus aorticus (Fig. 102). The other vessels should 

 have been tied in reinoving the heart, and the aorta and postcava 

 are left open for the injection. 



§ 842. Injection of Alcohol. —A. Into the left side. — Insert the 

 canula into the aorta so that the ligature about its tip may be just 

 centrad of tlie emergence of the first intercostal artery. Tie it in 

 place, and prepare a second ligature for t}dng it after the injection. 



Naturally, the progress of the alcohol is checked by the semi- 

 lunar and bicuspid valves, but it may be caused to pass them by 

 holding the heart with the apex up, and manipulating the base of 

 the aorta and the base of the left ventricle. When the auricle and 

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