The Microscope. 2tt 



sel, large for the size of the animal, and usually gorged with 

 food, or its remains. It is a conspicuous object and may be read- 

 ily removed. After i-emoval it must be slit open, so that the 

 inper surface shall lie upward toward the objective. To do this, 

 my plan is with great care to insert a fine needle into the lumen, 

 the cavity of the intestine, and when the tube has been placed 

 on the steel without having its wall pierced at any point, it is 

 gently rubbed with another needle until it is slit from end to 

 end. This is not a difficult thing to do if the needles be fine and 

 the microscopist's h^nd be steady. After the intestine, or a 

 part of it, has been taken from the body, all subsequent manipu- 

 lations may and should be performed on the slide and in the cell 

 in which it is to be mounted. 



The intestine, slit open, is then placed in a small drop of 

 water, and while it still remains attached to the needle, is to be 

 gently freed by another needle and floated in the water, inside 

 upward. The intestinal contents are then to be washed away 

 by the repeated dropping of water. When thoroughly cleaned, 

 as may be known by the disappearance of all the brownish 

 faeces, drain off" the water and add one or two drops of a solu- 

 tion of methyl green, one of the aniline stains to be had of the 

 dealers in microscopical supplies. The dye acts rapidly, so that 

 from four to five minutes will usually be long enough to color 

 the parts sufficiently. Wash away the superfluous stain, drain 

 off the water, add a drop of diluted glycerine and apply the 

 cover glass, cementing it in place with shellac. 



A small piece of the intestine is all that is needed ; it is not 

 necessary to take the entire intestinal tube. I have found the 

 rectum, the posterior region nearest the external aperture, to be 

 free from faecal matter, and beautifully transparent. In this 

 part, too, the cells may be rather better displayed than in the 

 anterior regions. 



The cells are comparativelj'- immense, with conspicuous cell 

 walls, prominent nuclei with their enclosed nucleoli, and with 

 the structure of the protoplasm finely displayed. The latter may 

 be seen well with a good 1-5 inch objective, but of course with 

 greater satisfaction under a lens of higher power. A close, 

 small meshed network of the protoplasm does not seem to be a 

 constant and invariable feature of its structure, although in 

 many cells it is exquisitely demonstrable, while in many others 



