212 PRACTICAL HISTOLOGY. 



Moreover, in embedding a piece of one of the 

 membranous viscera it is well to place it, as a general 

 rule, so that the sections shall be exactly transverse 

 to the axis of the viscus, following, therefore, the 

 direction of the circular muscular fibres and cutting 

 the longitudinal across. When the direction of the 

 section is known, it is easier to understand the ap- 

 pearances w r hich the various parts present when cut. 

 Sections cut parallel to the axis of the viscus, and 

 taking therefore the direction of the longitudinal 

 muscular fibres, may be made with equal advantage, 

 but oblique directions should be avoided. 



Preparation 2. Bloodvessels of the gullet 

 The arrangement of the vessels is best shown in a 

 flat preparation. A small piece, obtained from an 

 injected animal, is transferred, without staining, 

 from the spirit to oil of cloves, being subsequently 

 mounted in dammar, with the inner surface upper- 

 most. Such a preparation is only useful for exami- 

 nation with a low power, but by this the arrangement 

 of the vessels in the successive strata can be well 

 made out. 



Preparation 3. The stomach. The stomach 

 should always be prepared as soon as possible after 

 death, for, in the first place, the columnar epithelial 

 cells covering the inner surface soon become altered ; 

 and secondly, if digestion were proceeding in the 

 organ at the time of death, the mucous membrane 

 itself becomes attacked by the gastric juice in a very 

 short time. 



The abdomen, therefore, is to be opened as soon 

 as the animal (a cat or dog) is dead, and the oesopha- 

 gus cut as near the diaphragm as possible, and the 

 duodenum about two inches beyond the pylorus ; 

 the folds of peritoneum connecting the viscus to the 

 liver and neighboring parts are also severed, and the 

 stomach is removed. If the organ is empty or if 

 the contents are fluid enough to admit of being 

 poured out through the pylorus, it may be prepared 

 as a whole by distension with the spirit and chromic 



