NATURE 



[September 12, 191 8 



circui -. inosculating with others in the 



■11 the watery contents of ill'-, pas- 



v. law - df movement depend* m ipon 



ipi and moi ' menl "I i he glai ii i . the 



hi. ill Mains anil cracks in the ici . and 



ol temperature from above downwards. 

 lias bei n said in indicate that if in the 

 section el ice we an- considering the temperatun ap- 



ln's close tn IVc('/inL:-|Hiini, the channels of 

 ing fluid which encircle the n\stals would per. 

 in. aie the glacier down in a definite point where, if 

 the mean annual temperature w re low enough, the 

 ice would he solid and impervious. We are led in 

 suppose From Buchanan's observations that the critical 

 temperature of solidification may be as low as 13 ('.. 

 though in Antarctica, where the ice is purer, it should 

 be -)° or g° higher. Granting that such a temperature 

 may he several degrees from the actual truth, we 

 may at least he sine thai for 5 below the free/inn. 

 point of fresh wan 1 ihe glacier-ice of Antarctica is 

 pervious tn bacteria, and contains a medium suitable 

 for their reproduction. 



Tn Adelie Land the mean annual temperature at 

 sea-level lies between 15 and -20 C, but on 

 mounting the plateau which falls steeply to the coast, 

 the temperature descends at the rate of almost 4 for 

 every 1000 ft. In the summer-time the shade tem- 

 perature r agister 1 d on sevi ral occasions 5-5° C. (40 F.), 

 and for three months at least the temperature, except 

 for unusual fluctuations due to blizzards, never fell 

 much below - io° C, and was verv often close to 

 o° C. Considering, too, that there is a verv appre- 

 ciable amount of sunshine between the equinoxes, the 

 period during which bacterial life and growth would 

 be possible might be extended, during a favourable 

 summer, up to four months. The action of sunlight 

 is nl paramount importance in promoting a thaw 

 throughout the ice canaliculi, especially when we 

 remember that the shade temperature in.iv register 

 o° C. at the same time as Ihe thermometer in the 

 sun rises to 16 C. 



The important Doint at issue is that the northern 

 slopes of the glacier fall towards the sea at such an 

 angle that the rays o{» the sun for some months 

 during the summer are norma! to the surface, thereby 

 increasing the intra-glacial thaw, and for short periods 

 causing the temperature of the whole mass in the 

 lower latitudes to rise within a few degrees of 

 freezing-point, the optimum temperature of the micro- 

 organisms of ice and snow. At the south geographical 

 elevated to ro.000 ft., the obliouity of the sun's 

 ravs and the low temperature would not encourage 

 bacterial life except in the surface lavers of snow, 

 and that onlv for a few weeks at the summer solstice. 

 Assuming that the greater part of the continent is 

 at a more or less uniform height of 6000 ft., we 

 should conclude that the organisms which descend from 

 the ail n buried In a certain depth, wholly 



deprived ni .1 free-swimminP existence, until in the 

 nlenitude of ages thev arrive at that northern 

 boundarv where thi summer thaw begins. 



It will he apposite now tn review the few observa- 

 tions which w.i made mi snow before passing to a 

 few remarks on the meteorology of the southern 

 hemisphei. : 



d) Gram-posith ; I -ram-negative, sporing 



bacilli crew in culture from snow of a sastrusja or 

 snow-wave one-third of a mile south-east of the Hut. 



(2) On three occasions when falling snow was 



'athered in a sterile basin, elaborate precautions 



having been taken to prevent contamination, the 



d-ont samples showed under .-. cover-slip cocci, 



bai illi. and, invariably, zooglcea masses of bac- 



in moderate numbers. Diplococci, and occa- 



XO. 2550, VOL. I02] 



sionally cocci, were observed to be invested by a 

 pale capsule. In ter in 



the form of vegetable cells was noted. 



(3) A glucose agar slope culture nf falling snow 

 showed a few small greyish colonies, which wire nut 

 examined. 



Slender as these results are, they be'eome nf more 

 importance when correlated with the many pos 

 findings made in glacier-ice- the vast 



falling snow. The) am meaningless, too, unless 

 considei the probable origin of the bacteria which 



1 liny In the 1 r\ sta's nf snow. 



Regarded simply, the circulation of air in the 

 southern hemisphere has certain main characteristics 



a widespread uprush from equatorial, tropic, and sub- 

 tropic zones; a continuous flow al a high level towards 

 ihe southern continent; a subsidence nf mk i • 

 layers ol cool air, increasing in density and coincident 

 with a rising barometric pressuri : a concentration ol 

 air al high barometric pressure over the vast crown 

 nf lull-, Antarctica; a relief of pressure in the tor- 

 rential luiists of blizzards through tn the low-pn 

 belt nf the Southern Ocean, and, in wide terms, the 

 genesis nf a low equatorial return current modified 

 and deviated by such factors as earth-movement, lati- 

 tude, disposition of island, sea, and continent, 

 configuration of the land. 



Bacteria or their spores maj be found in the 

 sphere fr.c, incorporated with minute parti' I. 

 aqueous vapour, or clinging to small foreign I" 

 With these foreign bodies or dust-motes we know that 

 the) ascend under the impetus of rising equatorial air 

 into the atmosphere to a considerable height, until at 

 length thev come under the influence of the ^nat 

 poleward-flowing current. The bacteria mi anwhile 

 have cooled, become paralysed, and, either singly or in 

 segregated masses, thrown out their protective capsule 

 of protein material. They travel to the Pole, and 

 here are frozen to spicules nf ice or with the dust 

 which has conveyed them are attached to crystalline 

 snow-flakes, sinking lower with the descending strata 

 of air, and alighting at last on the surface of the 

 plateau. 



And novv, sparse or in numbers, the frozen 

 organisms, extruded with the dust-mol they accom- 

 panied to the periphery of the nucleai snow-crystal, 

 commence a new life-history. 



When the snow-flakes — on the plateau nf Antarctica 

 -now is mostly in th; form of sago-like granules have 

 recently fallen, thev lie together in s,,ft, downy, 

 flocculent heaps enclosing, in proportion to the spai 1 

 thev occupy, a large volume of air. Under ill. in- 

 fluence nf gravity and the pressure of the wind, and 

 in dependence, ton. on the temperature and humidity 

 of the air, die snow becomes denser and more com- 

 pact, the enclosed air is expelled, and the snow- 

 crystals increase in size. Thus we ma] conceive that 

 the bacteria lend to be expelled into the inti 1 

 between separate crystals, where the) await tin- time 

 when the temperature will rise sufficiently to providi 



a liquid medium in which theii lii I pecies mat be 



Mil' wed. If the temperature still remains ten low for 

 liquefaction of the comparativelj in n snow adher- 

 ing around the primary pure crystal, the slow meta- 

 morphosis ol the snow into nivi goes on under more 

 or 'ess drv conditions. 



In conclusion, if we tface out briefl) the subsequent 

 historv nf these bacteria of ice and snow, we see them 

 in the slew northward surge of the glacier set floating 

 in ice-ton [ues and herns nf th.- Antarctic Ocean, where 

 thev gradually thaw out and probably become accus- 

 tomed to h' salinity of the sea. They circulate 

 throughout the immense volume of water, cling,,, 

 the plankton of the surface, travelling to various 



