To give an idea of the prevalence of appendicitis, I may mention that in a single Paris hospital (Hôpital Trousseau) four hundred and forty-three cases of the disease have been treated in the five years 1895–1899.[75] In many of these cases the subjects were infants, as these as a rule are much more subject to appendicitis than are the aged. According to Treves,[76] the well-known English surgeon, 36 per cent. of the observed cases were under twenty years of age. Among old men, on the other hand, appendicitis is a rare exception. The varying incidence of the disease at different ages no doubt depends on the fact that in old age the appendage is often obliterated. The more easy communication with the other portion of the gut may be, the more chance there is for inflammation to occur. As it has a muscular layer, the appendage is able to void its fœcal contents; and a Scotch surgeon, Parker Syms,[77] has seen an appendage that he had removed, in the act of writhing about like an earthworm. Such movements, undoubtedly, would aid the discharge of the contents of the cavity. The movements of the appendage, however, are usually feeble, and thus stagnation of the contents is common. Foreign matter is often found in the cavity, such as the pips of fruit, seeds, hairs, thorns, and in rare cases pins or even tin-tacks. Such bodies are capable of wounding the inner wall of the appendage, and so giving an opportunity to the microbes that abound in the digestive tube, with the result that microbial infection and inflammation of the organ is produced. Often, too, intestinal worms pass into the appendage and become the carriers of pathogenic organisms. Appendicitis is usually a grave disease, and is fatal in from 8 to 10 per cent. of cases. It would be difficult to find anywhere else in the human body so flagrant a case of natural disharmony. The organ in question may be obliterated or removed without disturbance of function, and, moreover, in its normal condition is a frequent cause of serious illness! The vermiform appendage is not the only part of the digestive canal that is out of harmony with the maintenance of life and health. The cæcum itself, of which the appendage is only a portion, is degenerating in the human body, as I stated in the last chapter. The human cæcum, in fact, is very little developed in comparison with the cæcum of most herbivorous animals, in which it is a true organ of digestion. In the human embryo the cæcum and the appendage are relatively better developed than they are in the adult.