July 6, 191 6] 



NATURE 



391 



as they present aspects of biochemistry and cell- 

 functioning in a relatively simple form free from many 

 of the complications encountered with higher organisms. 

 One such problem is the activation of enzymes which 

 is sometimes produced by the presence of living cells. 

 The author observed, for instance, that certain kinds 

 of starch granules, capable of resisting indefinitely the 

 action of a highly diastatic liquid in which they were 

 immersed, were readily attacked by the diastase after 

 a trace of yeast had been added. Possibly the ex- 

 planation is to be sought in the reversible nature of 

 enzyme action and the continuous removal of certain 

 products by the yeast. The subject may perhaps 

 throw some light on the influence of "vitamines" on 

 animal nutrition. The allied problem of symbiosis is 

 exemplified in a relatively simple form by the " amylo- 

 process " employed in certain distilleries at Seclin, in 

 France. In this process the sterilised amylaceous 

 material is saccharified and converted into alcohol and 

 carbon dioxide in one operation by the joint action of 

 a mould fungus which produces diastase, and a yeast 

 which effects fermentation. Another subject which 

 should be of interest to the physiologist relates to the 

 quantitative relation, between the reproduction of yeast 

 cells and the supply of oxygen available. The author 

 found that when cells are sparsely distributed through 

 a nutrient liquid the oxygen initially dissolved in the 

 liquid is rapidly absorbed by the cells, and the 

 "oxygen-charge" per cell thus taken up determines 

 the reproductive capacity of the yeast, provided no 

 further oxygen is available. The author gives further 

 examples of the extension of scientific knowledge re- 

 sulting from the study of brewing problems, and 

 discusses at length some of the more technical matters 

 which still await solution. 



THE PLAINS OF NORTHERN INDIA AND 



THEIR RELATIONSHIP TO THE HIMALAYA 



MOUNTAINSA 



A HUNDRED years ago the accepted idea was 

 -^"^ that mountain ranges were due to the upward 

 pressure of liquid lava, and that their elevation had 

 been caused by volcanic forces. But when geologists 

 began to study the structure of rocks, they found that 

 mountains had suffered from horizontal compression, 

 which was evident from the folding of strata. 

 This discover^' led to the idea that mountains had 

 been elevated, not by vertical forces, but by horizontal 

 forces, which squeezed the rock upward. The 

 wrinkling of the earth's crust into mountains by 

 horizontal forces was explained by the cooling of the. 

 earth ; this is the well-known contraction theory ; the 

 earth's interior is held to cool and to contract, and the 

 outer crust is supposed to get too large for the shrink- 

 ing core and to wrinkle. 



About i860 the observations of the plumb-line 

 brought to light a most important and totally un- 

 expected fact, namely, that the Himalaya were not 

 exercising an attraction at all commensurate with their 

 bulk. 



The plumb-line was observed at Kaliana, 60 miles 

 from the foot of the mountains ; the observers found 

 that the Himalaya were exercising no appreciable 

 attraction. By the theory of gravitation the plumb- 

 line ought to be deflected at Kaliana .^8 seconds 

 towards the hills. It is not deflected at all ; it hangs 

 vertically. This discovery was the first contribution 

 made by geodesy to the study of mountains. The dis- 

 covery was this, that the Himalaya behaved as if 

 they had no mass, as if they were an empty eggshell ; 



1 Abrideed from an addreii to the Tndian Science ConereM at Lncknow 

 on January 13 by the president, Sir Sidney Burrard, F.R.S. 



NO. 2436', VOL. 97] 



they seemed to be made of rock, and yet they exercised 

 no more attraction than air. From the Kaliana ob- 

 servations Pratt deduced his famous theory of moun- 

 tain compensation ; he explained the Kaliana mystery 

 by assuming that the rocks underlying the mountains 

 must be lighter and less dense than those underlying 

 plains and oceans. The visible mountain masses, he 

 said, are compensated by deficiencies of rock under- 

 neath them. This is the theory of mountain compensa- 

 tion. The compensation of the Himalaya is not be- 

 lieved now to be exactly complete and perfect ; they 

 seem to be compensated to the extent of about 80 per 

 cent. ; their total resultant mass is thus about one-fifth 

 only of their visible mass standing above sea-level. 

 The discovery of mountain compensation struck a blow 

 at all theories which attributed the elevation of moun- 

 tains to any additional masses that had been pushed 

 in from the sides. The elevation of mountains by 

 subterranean lava squeezed in from the side had to be 

 rejected because it gave to mountains additional mass ; 

 the w-rinkling of the earth's surface by lateral hori- 

 zontal forces had to be rejected because it gave to 

 mountains additional mass pushed in from the sides. 

 As the Himalaya possess only one-fifth of their appar- 

 ent visible mass, I am led to suggest that the prin- 

 cipal cause of their elevation has been the vertical 

 expansion of the rocks underlying them, vertical ex- 

 pansion due to physical or chemical change. 



Mountains Originate at Great Depths. 



A very important work has been that of Mr. Hay- 

 ford, who has recently discussed the results of the 

 plumb-line at a large number of stations in America. 

 He has confirmed Pratt. 'Hayford has investigated 

 the depth to which the deficiency of density underlying 

 mountains goes down, and he has found that that 

 depth is between 60 and 90 miles. That is to say, he 

 has shown that the depth of subterranean compensa- 

 tion is very great compared with the height of moun- 

 tains. The discovery that mountains originate from 

 the great depth of 60 to 90 miles is the second impor- 

 tant contribution of geodesy to this study. The first 

 was compensation, the second is great depth. 



Southerly Deflections Prevail over the Ganges Plains. 



Now let me tell you of the third discovery due to 

 this plumb-line. The survey found that at 60 miles 

 from the hills this plumb-line hung vertically, and 

 Pratt deduced the theory of mountain compensation. 

 But when the survey began to extend their operations, 

 a new phenomenon came to light, which caused great 

 surprise. All over northern India at distances exceed- 

 ing 70 miles from the hills, this plumb-line was found 

 to hang decisively away from the mountains ; here at 

 Lucknow it is deflected 9 seconds to the south. 

 If the Himalaya were simply compensated, this 

 plumb-line should be hanging at Lucknow 

 exactly vertical ; if the mountains were not 

 compensated, it should be defkcted here about 50 

 seconds towards the north. But it is deflected 9 seconds 

 towards the south. The observers were astonished to 

 find that at places in sight of Himalayan peaks the 

 plumb-line turned away from the mountain mass ; that 

 at .\mritsar, in sight of the Dhauladhar snows, it was 

 deflected towards the low Punjab plains ; at Bombay 

 it was deflected seawards away from the Western 

 Ghats ; on the east coast of India it w^as deflected sea- 

 wards away from the Eastern Ghats. 



The new lesson to be learnt from the plumb-line 

 is this : a hidden subterranean channel of deficient 

 density must be skirting the mountains of India. 

 Here in North India is a wide zone of deficient densitv, 

 of crustal attenuation ; it is the presence of this zone 

 of deficiency that accounts for the southerly deflection 



