586 



HEART. 



as stated by Cloquet and Cruveilhier, is as 

 5 to 4. The right ventricle is generally found 

 larger than the left after death. This difference 

 has been very variously estimated by different 

 anatomists. Some, as VVinslow, Senac, Haller, 

 Lieutaud,* and Boyer, have maintained that 

 there is a marked disparity between the capa- 

 cities of the two cavities, while Meckel, 

 Laennec, Bouillaud, Portal, and others be- 

 lieved that this difference is to a smaller extent. 

 Lower was the first to maintain that both 

 ventricles are of equal size. Sabatier, Andral, 

 and others have supported this opinion ; while 

 Cruveilhierf states that he has satisfied himself, 

 from comparative injections of the two cavities, 

 that the left ventricle is a little larger than 

 the right. Gordon has occasionally found 

 both ventricles of equal size, and Portal has 

 seen them of the same size in young persons. 

 Santorini and Michelattus believed that, though 

 the capacity of the left ventricle appears a 

 little smaller than that of the right, yet that 

 the superior force of the left auricle over the 

 right dilates the left ventricle sufficiently to 

 render it equal to the right. 



The majority of anatomists, however, have 

 always maintained that the capacity of the 

 right ventricle is greater than that of the left, 

 and have adduced the following arguments in 

 support of this opinion: 1, that the right 

 auricle, right auriculo-ventricular orifice, and 

 origin of the pulmonary artery are larger than 

 the auricle and corresponding orifices of the 

 opposite side : 2, that when both ventricles 

 have been filled with water, mercury, or wax, 

 more of these substances is found contained 

 within the right than the left : 3, the experi- 

 ment of LegalloisJ shew that when an animal 

 is bled to death, this disparity between the 

 size of the ventricles is still found. Those 

 who maintain that the capacity of these two 

 cavities is equal do so on the following 

 grounds: 1, that as the walls of the right 

 ventricle are weaker than those of the left, 

 when the same force is used in injecting both, 

 the right must, as a matter of course, be more 

 dilated than the left. 2. Sabatier ingeniously 

 suggested that, as during the last moments of 

 life the passage of the blood from the right side 

 of the heart is generally impeded, producing 

 engorgement of that side, while the left side 

 was generally empty, this might account for 

 the greater size of the right ventricle. 3. 

 Sabatier and Weiss maintained that in those 

 cases where the kind of deatli was such that 

 the right side of the heart could not be en- 

 gorged as in fatal haemorrhage, no difference 

 between the capacity of the two sides could 



* Memoires de 1'Academie Roy. des Sciences, 

 t. viii. p. 561, 1754. Lieutaud's authority is some- 

 times quoted in support of the opinion that these 

 cavities are of equal capacity. 



t Anatomic Descriptive, t. iii. 



J Dictionnaire des Sciences Med. t. v. p. 436. 

 These experiments were performed upon dogs, cats, 

 guinea-pigs, and rabbits. 



De dextro cordis vcntriculo post mortem am- 

 pliore* 



be observed. 4. The experiments of Sabatier, 

 in which, after tying the aorta and producing 

 engorgement of the left side of the heart, 

 while the right side was emptied by a wound 

 made into the vena cava or pulmonary artery, 

 the left ventricle was found to be of greater 

 capacity than the right. 



M. Bizot maintains that the capacity of the 

 ventricles goes on increasing from youth up 

 to old age; and that this, contrary to the 

 opinion of Beclard, is not so rapid in old 

 age as in the earlier periods of life. The 

 following are a few of M. Bizot's measure- 

 ments: 



Left ventricle, male. 

 Age. Length. Krcadth* 



1 to 4 years 20 lines. 31 lines. 



50 to 79 years 36 56| 



Average from 15 to ) .,. ,. 



79 years <i . rf " * " 



Left ventricle, female. 



1 to 4 years 18| lines. 29| lines. 



50 to 79 years 31 49J 



Average from 15 to ) , , . 



89 years \ " 48 ^ 



Right ventricle, male. 



1 to 4 years 20J lines. 47J lines. 



50 to 79 years .... 37* 87 



Average from 15 to ) _,, ,, 



79 years S 37 ^ " S2 *> " 



Rig/it ventricle, female. 



1 to 4 years 18J lines. 44J lines. 



50 to 79 years 35{^ 76 



Average from 15 to ) _-, 



89 years \ 3 ' " 



Every one must confess that the right ven- 

 tricle is generally found larger after a natural 

 death in the human subject than the left; and 

 it appears exceedingly probable that these two 

 cavities, in the healthy state of the organ, 

 contain different quantities of blood during 

 life. As the capacity of the auricles is rather 

 smaller than that of the ventricles, it may 

 be asked how can the auricles furnish blood 

 sufficient to distend the ventricles? We shall 

 afterwards more particularly explain that the 

 blood passes from the auricles into the ven- 

 tricles at two different times during the interval 

 between each contraction, viz. at the moment 

 of its relaxation, and again during the con- 

 traction of the auricles. Various attempts 

 have been made by those who maintain that 

 the right side of the heart is larger than the 

 left, to explain how the equilibrium of the 

 circulation can be maintained. Helvetius* 

 supposed that this could be accounted for 

 by the diminution which the blood suffered 

 in passing through the lungs ; and in proof 

 of this he erroneously maintained that the 

 pulmonary arteries were larger than the pul- 

 monary veins. Legallois believed that this 

 could be explained (as appears very probable) 

 by the greater size of the right auriculo-ven- 

 tricular opening, allowing a greater reflux of 

 blood back again into the auricle, during the 

 systole of the ventricles. 



Mcmoirc dc 1'Acod. Roy. 1718, p. 285. 



