PEEVIOUS FORAMEN OVALE CYANOSIS. 363 



as in the lower animals There are infinite varieties of arrest 

 of development, but the most interesting to the practitioner 

 is that of 



PEEVIOUS FOEAMEN OVALE CYANOSIS. 



I have mentioned at page 326, that in foetal life the two 

 auricles of the heart communicate by an oval opening. This 

 causes an admixture of the blood, returning from the system 

 with that returning from the lungs. After birth, the opening 

 is perfectly closed, and, if it remains open, the purified blood 

 from the lungs in the left auricle becomes contaminated by 

 blood which has been the round of the system, and returns of 

 a dark colour to the right auricle. The consequence is, that 

 venous blood circulates through the arteries, so that the visible 

 mucous membranes are blue, the development of animal heat 

 imperfect, and, in fact, all the functions of the body imper- 

 fectly carried on. From the blueness of the skin and visible 

 mucous membranes, this affection has received the name of 

 Cyanosis, or the blue disease. 



As pervious foramen ovale can only be a congenital state, 

 it is observed in young animals. It may prove fatal to them 

 at an early period of life, or, from their puny, sickly aspect, 

 their owners may, though in ignorance of the real nature of 

 the cause, resolve to destroy them. 



It may not be recognised until animals are handled in 

 breaking or training ; but the difficult breathing, the oppres- 

 sion resulting from even moderate exertion, with marked em- 

 barrassment in the functions of circulation, will turn the 

 attention of an observer to the heart. Auscultation reveals 

 an abnormal sound, which not unfrequently consists in the 

 murmur heard in ansemic patients, and due chiefly to the 

 condition of the animal. 



It would appear that it is possible to have the foramen ovale 

 re-opened in the human subject. I am not aware of a single 



