354 



KNOWLEDGE. 



September, 1911. 



from the fly as the ordinary individual observes them, and if a 

 piece of " media " is taken in the hand and the " flies " shaken 

 off on to a piece of white paper, they will be seen to move 

 about by a series of sudden sharp jumps, sometimes covering 

 a considerable distance in comparison with their own length. 

 They belong to the Order CoUembola and are referred to by 

 microscopists in popular language as " Springtails." To give 

 the reader some idea of the immense number found on a bed 

 I have on many occasions observed an area of four to six feet 

 (superficial) covered to a depth of one quarter of an inch. 

 These insects are not confined solely to the surface of the 

 bed. On digging out the " niedia " they will 

 be found to a considerable depth, but in 

 much smaller numbers. 



The next dwellers in this odorous habita- 

 tion are, strange to say, our very interesting 

 friends, the spiders. My friend. Mr. F. P. 

 Smith, some little time ago. identified a 

 collection for me as consisting of two species. 

 viz.. Porrhnmma niicroplitlialiiiii and 

 TiiicticKs simplex, the latter by no means 

 a common species. Both sexes of each were 

 taken. While on the subject of spiders it 

 may be interesting to mention that during 

 certain months of the year it is a common 

 spectacle to find in the early hours of the 

 morning the whole surface of the bed 

 covered with a network of webs. It is an 

 extremely pretty sight, and I have several 

 times endeavoured to take photographic 

 records, but without any satisfactory measure 

 of success. The spiders, like the " Springtails," appear to be 

 equally at home in the depths of the bed. In fact, they are 

 much more evenly distributed. 



On the bottom of the outlet channels there is usually a layer 

 of finely divided mud, or "humus" as it is termed, and on 

 skimming this layer one can generally obtain the Desmid 

 Clostcrhiin ciisis, but not in very large numbers. .Amongst 

 the Protozoa there are specimens of Arcclla. Actinoplirys sol, 

 and Difflti^ia. Coming to the Infusorians there are found 

 Coleps, Stcntor and VorticcUa, the latter forms sometimes 

 being taken in large numbers. The slipper animalcule 

 Paramoccium, it is almost 



needless to say, can always . — . — - — . 

 be found. 



.•\mougst the Entomostraca 

 specimens of Cyclops are 

 plentiful, together with Daph- 

 iiia piilcx. 



A few Rotifers are some- 

 times taken, and the same 

 remark applies to Voli^ox 

 glohafor and the freshwater 

 polype Hydra virUlis. 



The variety of microscopic 

 life would probably be larger, 

 but owing to the method of 

 working, and the constantly 

 changing character of the 

 sewage, it is somewhat sur- 

 prising to find the variety 

 herein enumerated. 



.A peculiarity which can perhaps be easily accounted for is that 



whilst it is possible to keep specimens of the forms mentioned 



in captivity for considerable periods of time, when the collection 



has been taken from a freshwater pool, this is not the case with 



those collected from this particular gathering ground. Vorti- 



cella and the larval forms of Cyclops die very quickly unless 



the collection is poured out into a shallow dish. In this way 



I have kept the several forms of life in an active condition for 



a considerable time. ,- ,, „ 



Geo. p. Deeley. 



ANABAENA CIRCINALIS.— The water in one of the 

 ponds near Totteridge Common, visited by the Ouekett 

 Microscopical Club on their Saturday afternoon excursion late in 

 June, was of a decided green colour, almost like green pea soup. 



Figure 1. Anabac/ia circiiujlis 



The appearance was caused by the presence of many different 

 species of minute algae, most of them of an indefinite charac- 

 ter, such as would be classed with the Protococcaceae and 

 Palmellaceae,with some Scciiectcsiiins and zoospores of various 

 kinds. But the greatest effect was produced by a less doubtful 

 plant. ■ It was so plentiful that it was not necessary to con- 

 centrate the take with the net ; it could be obtained abundantly 

 for examination by merely dipping a bottle into the water. It 

 obviously belonged to the not very easily discriminated family 

 — the Nostocaceae — and was probablv Atiabacna circinalis 

 (Figure II. It consisted of free-swimming short filaments, 

 composed of roundish cells averaging about 

 4a' in diameter, with bluish-green coarsely 

 granular contents. The filaments were 

 twisted into helical coils of from two to 

 six turns, or occasionally even more, often 

 very symmetrically arranged. Most of the 

 coils had intercalated in them a rather 

 larger quite spherical cell with clear con- 

 tents — the heterocyst. Sometimes a spore 

 also was present : these are oval, granular 

 and larger than the ordinary cells, V'egeta- 

 ti\e cells undergoing division were not un- 

 common ; in this case they were larger than 

 usual and more or less constricted in the 

 middle, according to the stage the process 

 had reached. A singular feature was, that 

 the direction of the spiral in most cases 

 changed at the heterocyst ; this is shown in 

 the top and bottom examples in the figure. 

 When the filament was a short one, this gave 

 rise to a peculiar M-shaped form with turned up ends, as 

 shown in the extreme left hand example. This form was 

 very plentiful. Various species of Anahaciia are not at 

 all infrequent in the freshwater plankton but the present 

 variety is certainly not very common. 



The specific determination of many of the lower algae is 

 very difficult with the text books at present accessible 

 to the ordinary microscopist, and everyone desiring to 

 study this interesting class must be anxiously awaiting 

 the appearance of Professor West's anticipated work, 

 with fuller details than were possible in his " British 



Freshwater .Algae " published 



in 1904. 



J. B. 





Figure 2. Hvdrnnis foctidiis \'ill. 



H VDkik-US FOETIDUS 

 iVILL). — In the August num- 

 ber of " Knowledge " (page 

 320), a note was published 

 on the above, but the subject 

 proved too difficult for photo- 

 graphy ; we are, however, now 

 able to reproduce drawings of 

 the plant (Figure 2). The lower 

 drawing represents a small, 

 sparsely-branched plant ; us- 

 ually the branches are much 

 closer together and of a more 

 filamentous character. Above, 

 on the left, such a branch is 

 figured, and shows the small 

 coloured bodies embedded 

 in the gelatinous matrix. On the right is a small piece 

 of a thicker stem, showing the same bodies and their arrange- 

 ment in that part, where they become more elongated and less 

 frequent than in the thinner portions of the plant. The magni- 

 fications are approximately X 25, X 70, and X ISO respectively. 



J.B. 



ENTAMOEBA COLL— In the Annals of Tropical 

 Medicine and Parasitology, Vol. V., page 111, appears a 

 paper by Dr. H. B. Fantham, " On the amoebae parasitic in 

 the human intestine, with remarks on the life-cycle of 

 Entamoeba coli in cultures." The3amoebae begin to encyst 

 on the culture-media which the author has been using, in 

 about four days, the cyst wall of each being formed by 

 differentiation at the periphery of the now rounded amoeba. 



