There are many ways to visualize cells and other structures under the microscope. If you want the structure to remain alive, you are more restricted in what methods you use. Here are some of the images you should have seen in the microscopy lab, as well as comments on the assignment.

Comments

Descriptions of specimens under different forms of microscopy (marked out of 4):

• do not describe anything as circular if it is not truly a circle...i.e. ellipses, ovals and irregularly-shaped structures are not circular

• be concise - there's no need to say "the nucleus was purple in colour"... it can't be purple in size or shape, right?

• the same goes for "the cell was oblong in shape"...'oblong' refers to the shape.

• describe something as if you were describing it to someone on the other end of a phone...and that other person had to draw it.

• in only one case did you actually describe a cell (the cheek cell)...in all other cases, cells were either not there (bone, starch granules), or were not typically visible at the magnification used (microorganisms).

• "dark" is not a colour. "The cells were dark in colour" is a sentence with no value.

Drawings (marked out of 8):

• please refer to the appendices in the lab manual, most of you lost marks for not following the guidelines.

Photos

Specimen	Bright Field	Dark Field	Polarization
Bone - Haversian System
Starch Granules - unstained
Starch Granules - stained			see notes
Cheek Cells
Live Microorganisms

Notes: The key to Dark Field is a crystalline structure or halo effect of the specimen; the background is dark, not necessarily blue. The blue background in the image of the stained potato starch granules is the result of looking through polarizing filters...when they are in the cross alignment, the background is back, and so too will be the specimen if it is not birefringent. The stained granules are not birefringent, so I have shown that they are there by not having the filters cross-aligned.

R.F. Lauff Department of Biology St. Francis Xavier University Antigonish, NS Canada B2G 2W5