THE TEETH. 59 



surface, a loose plexus of capillaries, 0*004— 0*006' " in 

 diameter, which also exhibits here and there upon the surface 

 distinct loops, from which the veins arise. The pulp appears 

 to contain no lymphatics, but its nerves^ are extremely abun- 

 dant. Arising from the well-known nervi dentales, there passes 

 into every fang a large trunk of 0*03 — 0*04, and besides, as 

 many as six or more, fine branches of 001 — 0*02'", which con- 

 tain fibres of 0*0016 — 0003'". They ascend at first without 

 any considerable anastomoses and only giving off a few fila- 

 ments j but in the thicker part of the pulp they form a rich plexus, 

 with elongated meshes and divisions of the nerve tubules, and 

 so gradually break up into fine primitive fibres of 0*001 — 

 0*0016'". I am inclined to think their final termination 

 is in loops, but I grant that so long as the primitive fibrils in 

 those loops which unquestionably do occur, have not been traced 

 from trunk to trunk, which no one has yet done, the subject 

 is open to doubt. 



The gum, gingiva, that portion of the oral mucous mem- 

 brane which unites the alveolar margins of the jaw and the 

 necks of the teeth, is a pale red vascular tissue, which is 

 tolerably soft, but feels firm on account of the subjacent hard 

 parts : it attains, where it lies upon the teeth, a thickness of 

 I — 1|"' and possesses papillae of a considerable size (of 0*15 — 

 OS'"; in old people they even reach 0*7"' in length, and like 

 the papilla filiformes are covered with secondary papillae), and 

 a pavement epithelium, which, between the papillae, has a thick- 

 ness of 0*23 — 0*4.'". I could find no glands upon the gum, 

 but care must be taken not to confound with them, certain 

 rounded depressions of the epithelium of 0*08 — 0*1 5'" in dia- 

 meter, with more cornified cells, which occur not unfrequently 

 upon its upper portions. 



§ 142. 

 Development of the teeth. — The development of the twenty 

 milk teeth commences in the sixth week of foetal life, by the 

 formation of a groove in the upper and lower margin of the jaws, 

 in which, up till the tenth week, twenty dental papillae gradually 

 make their appearance. Partitions are now developed, so that 



1 [The nerves of the alveolar periosteum and of the pulp, are particularly described 

 by Czermak (1. c. pp. 27, 28).— Eds.] 



