September i j. 1918 



XATC RE 



m.nii again in the inter-crystalline canalicnli of the 



an I ice, and fret oni • mon to live and ini 

 in the viable reticulum oi th< glacier. Such a specula- 

 tivi theor) ma; be the ki j to their cyi li 



Antarctica. 



Liquid containing salts in solution does not com- 

 plete!} Freeze at .1 temperature of o C. (32 I 

 this Factor is verj important in the man 

 low and highei forms ol Antarctic life. The late Mr. 

 [am Murra - 1 Sii Ei ni 5t Sha< kit ton's British 



Antarctic Expedition (1907-0), has contributed some 

 unique evidence oi the habits and powers oi 1 



to cold exhibited bj the rotifers and wjater-bears. 



"To test the degree of cold which they could stand, 

 blocks of 1 ul from the lakes (saline) and 



exposed to the air in the coldest weather of the whole 

 winter. By boring into the centre of the blocks we 

 found that they wen- as cold as the air. A tempera- 

 ture of — 40 F. did not kill the animals. 



"Then they were alternately frozen an. I thawed 

 weeklv for a long period and took no harm. i In j 

 were dried and frozen, and thawed and moistened, and 

 still thev liv.d. At last thej were dried, and tin bottle 

 containing them was immersed in boiling water, which 

 was allowed to cool gradual h . and still a 

 number survived. . . . 



"Such is the vitality of these little animals thai 

 they can endure being taken from ice at a minus tem- 

 perature, thawed, dried, and subjected to a tempera- 

 ture not very far short of boiling-point, all within a 

 few; hours ia range of more than 200° F.). . . ." 



It would seem that bacteria were the ideal denizens 

 o> an environment where, for the greater part of the 

 1!' visible life is banished, and when' their 

 minim- size, protective changes oi bum. and versatile 

 feaction to moisture, low temperature, and concentra- 

 tion of salts wotdd be mosl advantageous for existence. 

 Tin bacteria caught up in the frozen sea within the 

 liquid sludge of crvohydrates, which circulates between 

 th. crystals of Fresh-water ice, learn to live, and 

 probably multiply, in a medium of much higher con- 

 ation than the ocean to which they are accus- 



The question now- seems naturally to arise: How 

 are we to explain the existence and multiplication of 

 bacteria in ice? And to satish such a querj we 

 should endeavour to discover what is the ultimate 

 composition of ice. how the crystals of ice are inter- 

 related, and what are tin- intimate changes which 

 occur in a descending or rising temperature. 



We refer to Mr. ]. Y. Buchanan, 7 formerly of the 

 ChaUengei Expedition 11*74'. 1°' ,n '' most modern 

 \ i.w s of ice-formation. 



As a result of man; 1 h periments on the 



[1 - which ... cm in freezing non-saturated saline 



-..Unions, he finds that the Crystals formed by freezing 



.. saline solution are in their ultimate constitution 



free from -alt. That is to say that "the cr\sials 



formed in freezing a non-saturated saline solution are 



mire ice, and that the salt from which thev cannot 



be freed does belong to the adhering brine." There- 



we may imagine that when sea-water freezes 



iriman solidification which takes place is of the 



fresh-water content, the -^itt - in solution being re- 



jected into the channels which new exist between the 



pure crystals \~ the temperature is still further 



cretions of pur.- ice go 1.. the crystals, and 



the brine, stdl further CO d, remains in the 



channel! .1 meshwork. 



Buchanan makes the whole matter Derfectlv cleai 

 in 1I1.' following pass..-,, extending bis principl 

 purer forms of ire, such as glai ier-ice : — 



[tie Heart of the Antarctic. \w sir I . H. Shackleton, C.V.O. 

 N 



"All natural " > : iding rain-water, contain 



some foreign, and usually saline, ingredients. H « ■ 



1 hloride of sodium as th. type ..I sui li ingredii nts, 



appose a water to contait i |uantitj of this salt 



equivalent to one pai t 1 of 1 hlorine in a 



million parts of water, thei ;...■.. .. s,,i u ti n 



containing ooooi per cent. ..t chlorine, and it would 



begin to freeze and t.. deposi put 1 a tempera- 



of — 00001 C. ; and it would c. ue to do so 



until, say, 999, paiis of watei had - deposited 



1 !i. 1 < \\ ould tb.n remain t. >ai ts ol 



residual water, which would retain lb \..ul.l 



mi, therefore, o- 1 per cent . of chloi ine, 

 not Freeze until the temperature bad Fallen to — oi°C. 

 This watei would then deposit ice at temp- 1 

 becoming progressively lower, until when 900 more 

 pmts of ice had been deposited we should have 



too parts residual water, O! brine, as il ma\ no 

 .ailed, containing 1 per cent, of chlorine and remain 

 ing liquid at temperatures above — i-o° C. Whei 

 90 more parts of ice had beer deposited we should 

 have 10 parts of concentrated brine containing 10 per 

 cent, of chlorine, and remaining liquid as low as 

 — 13° C. In the case imagined we assume the saline 

 contents to consist of NaCI only, and with further 

 concentration the cryohydrate would no doubt 

 separate out and the mass become really solid. . . ." 



In the case of the glacier-ice of Adelie Land, which 

 we wish particularly to consider, one would expect the 

 ice to be very pure; in fact, the superimposed layers 

 formed from the snow which has fallen should be, 

 presumahlv, as fresh as distilled water. But assum- 

 ing, as we do, that a large amount of aerial dust is 

 distributed over the South Polar plateau, and that 

 atmospheric gases are combined with the snow, the 

 ice contains mineral constituents, without doubt, in 

 much more dilute solution than is present in the rain- 

 water of a more temperate climate. And, considering 

 that this contamination bv dust-motes has gone on 

 for countless aeons, the whole thickness of the polar 

 ice-cap is impregnated with minute foreign bodies. 



On dissecting a piece of the glacier W'e find that 

 a disintegration of the interlocking grains, similar to 

 that which occur? in upturned slabs of sea-ice, takes 

 place on its exposure to the warmth of the sun or to 

 a temperature iust below the freezing-point of fresh 

 water. As Buchanan savs. : "Under the influence oi 

 the sun's rays the binding material melts first, the 

 continuity of the block is destroved, the individual 

 grains become loose and rattle if the block be shaken, 

 and finally they fall into a heap. A block of glacier- 

 ice is a geometrical curiositv. It consists of a number 

 of solid bodies of different sizes and of quite irregular 

 shapes, yel thev fit into each othei as exactly and fill 

 soace as completely as could the cubes referred to 



above." 



Buchanan made his studies of ice on the Alpine 

 glaciers, which, in comparison with the ice-sheet of 

 Antarctica, move raoidly, and, of course, are grossly 

 contaminated bv soil, rock, and dust. Still, one of 

 1I1. fust phenomena we remarked when stepping on 

 I,, the ice-foot at < ape Denison, Adelie Land, was the 

 large amount of granular rubble which formed the 

 ,,f Mi.- glacier. In other words, the summer 

 -on bad thawed out all the cementing channels, 

 the crystals lay melting in a clear slush of liquid. 

 I, ..1 nni-m a few micro-millimeti ■ 



1 Mock of glacier-ice not completely sol 

 would be a veritable labyrinth of minute tunnels 

 with liquid containing salts in solution. In 



on the tunnels would be viable, so that a si n oi,> 



n might easilv pass from top to bottom of the 



block. The same lump, as an in of th. 



. would siiii be pei forati I' nous and 



2550, VOL. 102] 



