138 



ELEMENTARY OPEHATI0N8. 



Fig. 171.— Dissecting Poroeps. 



Fig. 172.— Bull-Dog Forceps. 



(a) Free dissection is that of a flap of skin from the tissues 

 beneath, to which it is only slightly adherent. Holding the skin 

 with the fingers, or the forceps, with one hand, and having the 

 bistoury or scalpel ia the other, the skin is raised as much as 

 possible and separated from the other tissues with a single stroke 

 of the bistoury, held as a pen or as a violin bow, the operator 

 dravring it towards him as much as possible. In the dissections 

 of flaps of skin, as those in theV, the T, the crucial, and the cres- 

 centic incisions, the strokes of the bistoury extend in length as 

 they approach the base, or the adherent portion of the cutaneous 

 flap. In the straight or elliptio incisions, on the contrary, the 

 strokes are longer at the beginning. "When the cellular tissue is 

 very loose, its separation from the skin is made with the fingers 

 or the blunt end of the scissors. This mode, called enucleation, 

 is often employed for some special forms of tumors, as the 

 fibroid, or fatty. 



(5) Limited Dissection.— The steps of this process are the same 

 as those of the preceding, excepting that the surgeon proceeds 

 by small strokes in order to avoid going too deeply into the 

 tissues, and leave the skin of a sufficient thickness. 



(c) Dissection hy Slices or Shavings. — The sMn being divided, 

 and the subcutaneous tissues raised with the forceps, the bistoury, 

 held flatwise, excises horizontally each layer of the structure by 

 a sawing movement. 



C. — Puncture. 



Properly speaking, this is a simple, special operation, designed 

 to penetrate into hollow parts, to explore the nature of tumors, to 



