PEOFESSOE HYETLS ANATOMICAL NOTES. 321 



the same might be done for the arterial system by means of these 

 isolated injections, and most beautiful and instructive preparations 

 can be obtained by injecting, with differently coloured materials, the 

 arteries of the conjunctiva, the mucous membrane of the nostrils, or 

 the lining membrane of the mouth, pharynx, urinary bladder, &c. 



The following results of a long series of such injections may 

 merit attention, as some of them are of high practical importance. 



COEONAEY AETEEIES. 



When a single coronary artery of the heart is injected, the other 

 (say the right) remains empty, showing that there is no anasto- 

 mosis between the primary, or secondary, ramifications of these two 

 arteries, in the circular and longitudinal grooves of the surface of the 

 heart, as all anatomists say they have observed. When the injection 

 passes from one artery to the other, it is always through the inter- 

 vention of the capillary system that the communication takes place ; 

 never through the ^oft-capillary system ; hence it follows, that the 

 right and left hearts are, to this extent, independent as far as regards 

 their arterial circulation. 



Aeteeia lingtjalis. 



The same is likewise the case with the right and left lingual 

 arteries. When the right lingual artery is injected with colouring 

 matter, only one-half of the tongue becomes coloured, the other half 

 remaining as it is. If the assumed anastomosis really existed between 

 the two arteries (forming an arch in the top of the tongue) the injec- 

 tion of the one artery would certainly fill that of the opposite side. 



Aeteeia laeyngea supeeioe. 



When the Arteria laryngea superior is separately injected, it is 

 necessary to put a ligature on the Art. thyreoidea inferior of the 

 same side, because there is a very extensive anastomosis between the 

 former and the laryngeal branch of the latter ; this anastomosis will 

 be found in the interior of the larynx (between the thyroid and cricoid 

 cartilages) ; perhaps this fact admits of, the following interpretation : 

 The superior laryngeal artery is not exposed to muscular compres- 

 sion, but the inferior thyroid, which gives a branch to the larynx, 

 may occasionally be compressed by vehement contraction of the 

 muscles under which it wends its way. The intra-laryugeal anas- 

 tomosis of both is so arranged, that the necessary supply of blood 

 cannot be stopped by such compression. 



