Natural lenses …

The photograph above is as about as far from Andreas Gursky’s careful constructions, described in the previous post, as it is possible to get.  It is a close-up of a green algal floc Heather noticed whilst on a walk around a local nature reserve.   I guess it fits the general description of “decisive moment” except that it takes a special sort of observer to find any interest at all in such an unprepossessing habitat.

Under the microscope, the floc turned out to be composed of filaments of Spirogyra, with a single helical chloroplast.  Members of this genus (and related genera such as Mougeotia) produce copious mucilage so are always slimy to the touch.  However, this mucilage makes it difficult for the waste gases produced by photosynthesis to diffuse away, leading to the production of bubbles within the mucilage mass.   The interest, today, however, was that these air bubbles are acting as tiny lenses through which it is possible to make out the individual filaments of Spirogyra.

The green floc beside a footpath in Crowtrees local nature reserve from which the other images in this post were derived. 

I should add the caveat here that the photograph was taken with the “super macro” facility of our Olympus TG2 camera but the end-product is, nonetheless, impressive.   It also offers us an insight into the world of the very earliest microscopists.  Anton van Leuwenhoek’s microscopes consisted of a metal plate which held a tiny sphere of glass which acted as a convex-convex lens capable of up to 266x magnification to a resolution of little  more than a micron (1/1000th of a millimetre) (follow this link for more details).  To give an idea of what he might have seen with this, the right hand image below used 400x magnification.

That, however, only tells us part of the story of Anton van Leuwenhoek’s genius.   Whilst we should not underestimate the skill required to make the lenses and their mounts, the other essential element is curiosity.   Curiosity is, itself, multifaceted: in a few weeks we will probably make a trip out to an old quarry where we know we will find several species of orchids, and maybe some excursions to locations new to us but where others have reported interesting assemblages.  That’s one type of curiosity.  However, simply looking harder at the habitats all around us involves a different type of curiosity: a recognition that there is more to know even about things we think we already know about.   The former broadens our experiences, the latter deepens them …

The algal floc at Crowtrees local nature reserve in close-up: left: an extreme macro view of a single bubble from the image at the top of the post and, right: filaments of Spirogyra photographed under the microscope.  Scale bar: 20 micrometres (= 1/50th of a millimetre).

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