Finding Microorganisms

Day 118: For some time now, I have been pinching up moss samples from various locations in my yard (and sometimes elsewhere) in the hopes of being able to find tardigrades (also known as "water bears" or "moss piglets") with the microscope. For months, I had been astonishingly unsuccessful with what should have been a relatively simple exercise, and I finally discovered that the problem lay in my technique. After agitating my moss samples in water, I had been trying to avoid picking up debris with the pipette. As I learned a few weeks ago, that was also why I wasn't picking up any tardigrades. The cover glass on the first slide I prepared successfully was held a bit too far aloft to get good focus on my subjects. A fragment of moss gave them far too much room to swim around, but I was able to observe at least half a dozen through the objective. My next several attempts were miserable flops, even though I'd taken the moss sample from the very same fence rail under similar weather conditions. This morning, I was almost certain I'd failed again with the sample I collected yesterday, but taking a second drop of water for examination brought this little character into view, stretching out and contracting as it moved across the slide almost too fast for me to capture with the camera. As it turned out, I had found a rotifer rather than a tardigrade, but it was exhilarating nevertheless.

Thrush Feather Study

Day 149: Today's post is being brought to you by angry birds. No, not "Angry Birds" (capital letters, referring to the game), but enormously cranky, territorial, aggressive, maybe even downright vicious Varied Thrushes. I've been rather concerned for the Thrush population in my yard after finding evidence which seemed to point toward a predator with a particular taste for Thrush. I don't know why I didn't catch on sooner to the true reason I was finding little pockets of Thrush feathers in the snow. I've certainly seen them attack one another often enough. Today it dawned on me: preceding the actual aggressive run, one or both competitors goes breast-to-the-ground as insults are exchanged. "Your mama was a robin!" "Was not! You're a chicken...chicken-chicken-chicken!" Then the dash commences, one bird running to, the other (the smarter one, I suspect) running from. Sometimes the pause before the salute of swords lasts up to ten seconds, plenty of time for soft, warm breast feathers to freeze to the snow. Given the abundance of the resource, microscopy was a given, resulting in the interesting discovery that the downier sections near the shaft are marked with knot-like, dark nodes (lower right). This fluffy portion insulates the angry bird's chest against the icy snow.

Dabbling In Bryos

Day 184: Lichenology and bryology go pretty much hand in hand, although I've avoided bryophytes as being way too complicated. Still, there are a few mosses I know and love, and a lot of bryos have enchanting multi-syllabic scientific names. Anyone who knows me as more than a passing acquaintance knows my love of words; it was only a matter of time before I fell to temptation. I was given a firm push at the lichenologists' conference when I discovered Bruce McCune had written a field guide to the Pacific Northwest's more common mosses, and of course I find field guides absolutely irresistible. I figured I'd start with something which looked easy (at least I hoped it would be as easy as it looked!). I was pretty sure my fence moss conformed to Dicranoweisia cirrata (ooooh, that's a good one), but the deal was clinched when I stuck a leaf under the dark-field microscope and it looked just exactly like the picture in Bruce's book. Well, that was fun! What's next?

Rainy-Day Adventures

Day 20: It's the time of the year when I struggle to find interesting material for my daily posts. That's not to say there's nothing interesting going on in my life. Indeed, I have lots of things to keep me occupied, and right now, the darkfield microscope is pretty close to the top of the list. As a direct result of its acquisition, it's been necessary for me to practice with the microtome to perfect my technique. I've also had to re-learn how to pull stains effectively. Although my pond-water samples haven't yielded up any particularly exciting results, I've found plenty of other things to play with. This morning's exercise was performed on a horseradish leaf stalk. The top four images show a cross-section stained with methylene blue, an unstained longitudinal section, an 800x view of the nuclear material in the same section, and another longitudinal section stained with eosin. The lower row shows an eosin-stained longitudinal section of an iris leaf, unstained epithelial tissue taken from the inside of my cheek, a smear of butter which shows the fat globules, and a piece of pear skin stained with methylene blue. The butter smear reminds me of Aboriginal art!

Darkfield Universe

Day 15: Anticipating the arrival of Christmas-present-to-self, I stopped at a murky local pond to collect water samples for examination. At home, I covered them with cloth to allow air circulation, and the following morning, I prepared concave slides from each jar and settled in at the microscope to look for protozoans and anything else of interest. I was hoping for hydrae or planaria among the vegetative matter, but found nothing but a pair of insect larvae and a few fast-swimming ciliates. Later in the day, I tried again with even poorer results, although one critter was a type I'd never seen. The only protozoans I know are those we covered in high-school biology! This feller was cute, shaped somewhat like a kiwi (the bird), busily using a long proboscis to feed itself algae. If it had had ears, it could have heard me muttering, "I bet I can't find another one like you when the darkfield gets here."

When the darkfield 'scope arrived on Friday, I assembled it and again prepared a couple of slides from each jar of pond water. In roughly two hours at the eyepiece, I may have observed as many as four individual ciliates during a diligent search, but not another "kiwi." I finally just gave up and took a photo of a galaxy of pond scum to celebrate the acquisition of a darkfield microscope. Darkfield microscopy allows for better viewing of detail by using diffracted (as opposed to incident) light. It is especially useful when looking at subjects such as fungus spores and lichen asci.