DISCOVERY 



101 



on the north side of the Acropolis near a steep postern 

 stairway. The " Sphairistra," which can only mean a 

 " court for ball games," must ha\-e been near at hand. 

 Plutarch describes the statue as Kfpi/Ti't'oji', a word 

 which has been rejected by the editors of the text 

 because no meaning could be found for it : its manu- 

 script authority, nevertheless, is excellent. ^ It has been 

 emended to read K£XriTC((jir, which has the straight- 

 forward meaning of " riding a horse," the statue thus 

 being equestrian. M. Oekonomos, however, retains 

 the earlier reading KepriTiijuiv and, from the connection 

 of the word with Ktpois, " a horn," he derives the word 

 which gi\-e? us the name of the game — a " game played 

 with horned sticks," or, if you like, the "game of 

 hook." It is noteworthy in this connection that the 

 place in which the statue of Isocrates stood was a 

 " court for ball games," and, further, that the attitude 

 of the central players on our relief is that of hooking 

 and not of striking, as in hockey. 



The style of this relief is very greatly different from 

 that of the first. It is by an inferior artist who was not 

 successful at unusual attitudes. He has failed to render 

 the grace and agility of the bending figures, though he is 

 more successful with the standing. The figure on the 

 extreme right, however, is clumsily outlined. From a 

 comparison of the faces of the figures — the most 

 conventional part about them — with coins of Athens 

 bearing the features of Athena of the early lifth century, 

 it seems most probable that the relief belongs to a 

 period about 495 B.C. 



Filter-Passers 



By R. J. V. Pulvertaft, B.A. 



The great fascination of science and discovery lies in 

 the search for that far-off shore where is attained the 

 final and indivisible truth — the last, remotest star, 

 the western continent, or the tiniest morsel of life 

 itself. It seemed to the pioneers who first sighted the 

 bacteria — those minute fungi, distant cousins of the 

 breakfast mushroom — that they had attained their 

 goal, and that Life could not live in narrower confines. 

 Yet to-day we hear of living creatures far smaller 

 than most bacteria, but of even greater importance in 

 the havoc they work to the human race. To this group 

 of living morsels has been given the name of " Filter- 

 passers," and, although they have baffled research 

 from the time of Pasteur to the present day, it would 

 seem that now at last we are beginning to understand 

 more about them. 



Let us consider the diseases believed to be caused 

 ' It occurs also in the lexicographer, Hesychius. 



by them first, and then discuss the methods used to 

 get into touch with them. First, and most important 

 in its universality, we have influenza ; small-pox, 

 hj'drophobia, scarlet fever, and measles are among 

 the commonest of diseases throughout the world of 

 man, and are attributed to the same group of organisms. 

 Foot and mouth disease is one representative of the 

 damage they do to the animal world, and distemper 

 in dogs another. Even the plant world suffers from 

 them. For instance, mosaic disease in tobacco plants 

 ruins many crops yearly, ^^'e notice that aU these 

 diseases are very infectious — infinitely more so, for 

 example, than the bacterial disease tj'phoid fever, 

 which can only be contracted by eating infected 

 material or injecting bacteria. We get the impression 

 that there must be a deadly mist arising from an 

 influenza patient — that the tiny creatures which cause 

 it must float like clouds of smoke through the air. 

 That fact alone would serve to incline us to the belief 

 that the fatal organism, whatever it be, is very tin\-. 



The Size of Filter-passers 



Its size is further emphasised by the property from 

 which it has derived its name — the power of passing 

 through a filter. The filters used by the careful 

 housewife to purify her water supply, and by the 

 bacteriologist to rid the fluids, witli which he works, 

 of bacteria, are of two kinds. The Berkefeld filter is 

 made by compressing an earth which consists of the 

 flinty skeleton of a microscopic plant known as a 

 diatom — an earth which is also used as a knife polisher 

 and a tooth-po^^•der. The solid mass formed by this 

 compression has little pores in it, and we can readily 

 believe, from the nature of it, that these pores will be 

 of various sizes. It has been estimated that particles 

 as large as a five-thousandth part of a millimetre — 

 •2 jx in the language of the bacteriologist — can pass 

 through the filter in some instances. The second kind 

 of filter is the Chamberland — it is made of unglazed 

 porcelain, and has much smaller pores. Perhaps we 

 should not be far wrong in assuming that any particle 

 which passed through it must be smaller than a 

 fiftieth part of a yu. 



Every filter-passer can pass through a Berkefeld 

 filter, some can negotiate a Chamberland, and one 

 has been described — the organism responsible for 

 mosaic disease in tobacco plants — which is even said 

 to be able to diffuse through gelatine. It seems, 

 however, in a high degree unlikely that particles so 

 minute as to diffuse in that way can really be alive at 

 all. 



But even a particle a five-thousandth part of a milli- 

 metre in size is far too small for us to imagine. The 

 tiniest drop of human blood contains seven miflion red 

 blood cells, and each of these is more than thirty times 



