Wednesday, 12 May 2021

Trypanosoma cruzi

Trypanosoma cruzi is a single-celled parasite, first described in 1909 by the Brazilian physician Carlos Chagas, and the causative agent of Chagas disease. It is a tropical vector disease that occurs in humans, among others, and mainly in South America.

Friday, 7 May 2021

Zeolites from La Crosa de Sant Dalmai volcano

La Crosa volcano, also called “La Crosa de Sant Dalmai”, shares the space between the Catalan municipality of Vilobí d’Onyar (in the lands of Sant Dalmai) and those of Bescanó and Aiguaviva. Located in the NE of Catalonia, in Girona.


It is a wide volcanic maar or crater (over 1.200 m, one of the largest in Europe) and low altitude (156 meters above sea level) formed by a phreatomagmatic eruption, produced by an explosion caused by groundwater in contact with ascending magma from the main chamber. The violent explosions have formed a ring of pyroclastic projections, formed both by juvenile materials (of basaltic composition, chalk, tuff and some volcanic bombs) and by fragments of subterranean rocks (igneous and metamorphic fragments). The phreatomagmatic origin of the Crosa maar differentiates it from the rest of the volcanoes in the area, in which strombolian eruptions predominate. It must be said, however, that within this phreatomagmatic volcano we find a smaller cone of the Strombolian type.

The eruptive period of La Crosa is between 7.9 and 1.7 million years (My), characteristic of the volcanic processes of the La Selva depression. The oldest in the Empordà region date from 12 to 8 My and the most recent, from La Garrotxa, are between 500,000 and 10,000 years old.

Figure 1. View of La Crosa de Sant Dalmai volcano, from the Can Guilloteres viewpoint.

Thursday, 6 May 2021

Luminous wood

On the images you can see a cross section of a thin stem of Tilia showing the annual rings which are composed of Xylem in botanical terms or wood in daily language.


At the beginning of the growing season in a temperate climate, the Cambium will produce larger Xylem cells with thinner walls. These large cells (earlywood) are formed because the tree needs a lot of sap after winter. The earlywood is lighter and more porous. At the end of the growing season, the Cambium will produce narrower cells with thicker walls (latewood). Thus latewood contains more matter and is less porous, so it will look darker. Earlywood and latewood, which are formed during the same growing season, make up one annual ring. The most recent growth rings are situated at the tree's periphery, under the Cambium which is between the wood and the bark.
 

Wednesday, 28 April 2021

Family Cochliopodiidae de Saedeleer, 1934

For this Amoeba see the excellent website of the world famous amoeba specialist Ferry Siemensma.

"DIAGNOSIS: Amoebae partially enclosed within a flexible cuticle or wall (tectum) usually covered with microscales (Cochliopodium) or with a dorsal fibrous cell coat without scales (Ovalopodium). The covering is open along the region of attachment to the substratum; with no well-defined aperture.

Amoebae in this family have been classified as testate amoebae by Page (1987b) but are included in this chapter because they resemble euamoebae at the light microscope level. Typically they have a distinct hyaline zone often with short subpseudopodia, and a prominent central granular hump."

Friday, 23 April 2021

Chestnut and the Motic Panthera U

While looking through my new stock of prepared slides, I came across this specimen, a section of a petiole of the Castanea sativa. The Castanea sativa or European chestnut is widespread in Europe and Asia, meanwhile also in other temperate zones. The chestnuts are consumed since ancient times by people. The tree can become very old.

It was not necessary to take multiple photos of the object and stack it. The coupe was cut perfectly flat. The section is stained according to the Wacker 3A procedure (Acridine red -Acriflavin - Astra blue).



Friday, 16 April 2021

Iodine, indispensable

For the photo, a tiny grain of iodine was applied over an object slide with a cover slip on top. After gently melting it over a spirit flame and then solidifying, a crystal structure appears, which can be seen with the help of polarization.

Tuesday, 13 April 2021

Daphnias - Some of the smallest and most common crustaceans

We all know some of the bigger crustaceans like shrimps, lobsters and crabs. But far from all crustaceans are as large as these. Daphnias are some of the smallest crustaceans in the world and can be found in almost all ponds, streams, lakes and other freshwater habitats. Their size ranges from a few hundred microns to around 5 mm for the largest species. Like other crustaceans, daphnias are covered in a hard exoskeleton for protection. Underneath this tough exterior are organs like a heart, a digestive tract, reproductive organs, an eye and a primitive brain. And because daphnias are mostly transparent, it's easy to observe their anatomy on your own.

In the back of the animal is a cavity used for protection of their embryos as they develop. After a few days the babies are fully developed, able to swim and feed, and ready to enter the real world. At some point the mother will lift her foot creating a small opening for the babies to swim out of. In a matter of days, the newborn are ready to reproduce themselves and these animals are therefore able to multiply rapidly when conditions are right.

The embryos on the left are fairly new, but the embryos on the right 
have developed eyes, are able to move and ready to be born

Wednesday, 7 April 2021

Widespread

Bryum argenteum or Silver moss is perhaps the most widespread moss in the world, although in many regions it is found primarily in human settlements. It is prevalent in atmospherically polluted areas. It can be found in large cities on tarred roads, on concrete structures (e.g. between paving stones, at the bases of walls, on roofs and windowsills) on soil as well as in waste areas, but also in more natural habitats.

Friday, 2 April 2021

What’s in a rat’s eye

The photos show various parts of the rat's eye. There are many similarities between the eyes of the rat and those of humans, but also some striking differences. A few of these are mentioned here.



The eyeball of the rat’s eye can be rotated to change the viewing direction without having to turn the head. What is special is that rats can move both eyes in opposite directions. This both horizontally and vertically. Researchers at the Max Planck Institute found this out in 2013 and were able to record this using high-speed cameras. They are able to keep an eye on the sky while also looking forward. They can interpret a double field of view. Probably this has evolved in the wild to deal with great threat to raptors.

Friday, 26 March 2021

Be eaten behind bars

The Venus Flytrap (Dionaea) is the most spectacular of the meat eating plants. The leaves of this carnivore consist of two parts that can close. When an insect or small spider is touching the tactile hairs when eating from the nectar present on the leaf surface, the folding mechanism is activated. The two parts of the leaf will close within the blink of an eye. ‘Bars’ prevent the victim from escaping. However, the plant cannot be fooled. To be sure that the prey is present, it must touch the six tactile hairs of the leaf twice. When touched once, the leaves will not close.

Venus Flytrap


The microscopic photo shows the glands that are on the inside of the leaf. These glands secrete the fluid that serves to digest the prey

Prepared slide by Lieder