122 SUKGICAL APPLIED ANATOMY. [Chap. VIII. 



the bleeding that follows the extraction of teeth much 

 of the blood is supplied by them. The gums are 

 particularly affected in mercurial poisoning, and are 

 also especially involved in scurvy. In chronic lead- 

 poisoning a blue line often appears along their margins. 

 This is due to a deposit of lead sulphide in the gum 

 tissues, which is thus derived : Food debris collected 

 about the teeth in decomposing produces hydrogen 

 sulphide, which, acting upon the lead circulating in the 

 blood, produces the deposit. The blue line, therefore, 

 is said not to occur in those who keep the teeth clean. 



The tongue. On the under surface of the tongue, 

 less than half an inch from the fraenum, the end of the 

 ranine vein can be seen beneath the mucous membrane. 

 Two elevated and fringed lines of mucous membrane 

 may be seen on the under surface of the organ 

 converging towards its tip. They indicate the position 

 of the ranine artery, which is more deeply placed than 

 the vein, close to which it lies. It is extremely rare 

 for the tongue to be the seat of congenital defect. The 

 author of the able monograph on the tongue in 

 Holmes' " System of Surgery " has discovered only 

 one instance of congenital absence of the organ. 

 Fournier gives a case where the tongue was so much 

 longer than usual that the chest could be touched 

 with its tip while the head was held erect. 



In rare cases the fraeimm lingua; may be 

 abnormally short, constituting the condition known 

 as " tongue-tie," which is really a very uncommon 

 affection. The frsenum when divided should be cut as 

 near the jaw as possible, so as to avoid the ranine 

 vessels. Division of these vessels in relieving tongue- 

 tie has led to fatal haemorrhage, the bleeding being 

 encouraged by the efforts of sucking. " If the frsenum 

 and subjacent muscle fibres be too freely divided, 

 energetic sucking on the part of a hungry child may 

 tear the wound of these very lax tissues farther and 



