N the beginning of this month a pond in the Finchley Road, a little beyond the Highgate Archway, supplied some more specimens of the Pterodina patina, described in a previous chapter; but towards the middle of the month a visit to Chipstead, in Surrey, enabled a new region to be explored.
It is always a treat to a Londoner to get down to any of the picturesque parts of Surrey; the trees exhibit a richness of foliage and variety of colour not seen within the regions of metropolitan smoke; the distance glows with the rich purples so much admired in the pictures of Linnel, and the sunsets light up earth and sky with the golden tints he is so well able to reproduce. Probably the warmth of the soil, and the purity of the air, may make Surrey ponds prolific in microscopic life; but of this we do not know enough to make a fair comparison, although our own dips into them were tolerably lucky.
Walking one day down a lane leading towards Reigate, where the trees arched overhead, ferns grew plentifully in the sandy banks, and the sunlight flitted through the branches, and chequered the path, we came to a shallow pond, or great puddle, which crossed the way, and near the edge of the water the eye was struck with patches of crimson colour. On attempting to take up a portion of one of these patches the whole disappeared, although when the disturbance ceased the rich colour again clothed the dingy mud. The appearance was caused by thousands of little worms, belonging to the genus Tubifex, not uncommon in such situations, who thrust themselves out to enjoy the light and air, and retreat the moment an alarm is given. Probably both actions belong to the class described in the last chapter, as "reflex;" but it would be interesting to know whether creatures so humble have any sense of fear. These worms will repay observation, but in these pages we eschew all their tribe—unless the rotifers be assigned to them—and take ourselves once more to our especial subjects.
Cryptomonad—Euglena.
Knowing that farm-ponds are usually well stocked with microscopic game, we made a dip into one more especially assigned to ducks, and obtained wondrous little for our pains. We were not, however, discouraged, but made an examination of the circumstances, which determined a particular course of action. Our piece of water was simply a dirty duck-pond, in which no large plants were growing, and which did not even exhibit the little disks of duckweed that are common to such situations. There was, however, on the surface, in parts, an exceedingly fine scum of pale yellow green, and this, armed with a teaspoon, we proceeded to attack. By careful skimming, a small bottle was half-filled with minute organic particles, which were likely to be interesting in themselves, and pretty sure to be the food for something else. A small drop was placed on a tablet of the live-box, flattened out by the application of the cover, and viewed with a power of two hundred linear, which disclosed swarms of brilliant green globes, amongst which were a good sprinkle of minute creatures, like the Euglenæ already described, and whose little red eyes contrasted vividly with the prevailing emerald hue.
Cryptomonad.
One of the higher infusoria, whose species I could not identify, was devouring them like a porpoise among sprats. It did not, however, exhibit any sense in its hungry career; it moved about in all directions, gulping down what came in its way, but often permitting the escape of the little green things that were almost in its mouth. The little globes rolled and whirled about without the faintest indication of a purpose, and without exhibiting any instrument with which their locomotion was effected. To find out how this was done, a higher power was used, and from their extreme minuteness an amplification of seven hundred and twenty linear was conveniently employed, although a lower one (three or four hundred) disclosed the secret by showing that a little whip was flourished about through the neck, which the lower power revealed. When highly magnified, each little globe was seen to consist of an outer case of a reddish orange colour, which was noticeable on looking at the edges, although in the centre it was transparent enough to show the brilliant green contents, that resembled the chlorophyll, or green colouring matter of plants. From a short neck proceeded the whip-like filament, which was lashed and twisted about in all directions. These little creatures belong to the monad family, but whether they are to be called Trachelomonads, or by some other hard name, the learned must decide.
The 'Micrographic Dictionary' puts a note of interrogation to the assertion of some writers that Trachelomonads have no necks, and draws some with such an appendage.