KNOWLEDGE. 



[Ja-vuaey 1, 1900. 



floated was probably shielded from ascending currents 

 by the cloud-floor, and in the hour before sunrise the 

 upper levels had doubtless subsided into an exceedingly 

 quiescent and homogeneous state. 



The cloud-floor itself, or rather its upper face, was 

 worthy of the close attention which we were ready to 

 give it through many long hours. Speaking generally 

 it seems to have passed through three distinct stages. 

 First and earliest, it presented a fluffy cotton-wool 

 appearance, or perhaps could be better described — at 

 least when viewed from a thousand feet or more above 

 it — as wearing the appearance of recently fallen snow, 

 lying deep but light and feathery. 



Later on this seeming snowfield, interminable in 

 extent, appeared of harder surface and more compacted 

 like even snow when it has ])een subjected to bright 

 winter sun for several days. Then in the end — a.s 

 though to complete the analogy — these snow plains com- 



1 p.iu — Lioud-Hoor as though thawing into holloas. 



menced breaking up infinitely slowly, into black pits 

 and hollows through which the actual earth, though 

 several thousand feet below, began to show itself. 



The tri\'ial incident of our having suddenly found 

 a big blue fly buzzing noisily about us, when hang- 

 ing at a height of 8,000 feet, would have passed 

 without serious notice but for certain correspondence 

 which has since arisen. Mr. F. T. Wethered, of the 

 Alpine Club, writes to say that he has seen a butter- 

 fly scudding across the summit of the Grandes Jorasses 

 at a height of 13,7 99 feet, and sees no reason why the 

 fly should not have been on the wing and not taken up 

 in the car as we had supposed. M. C. Flammarion tells 

 of white butterflies fluttering round his balloon at 3,280 

 feet, though in the same voyage he remarks on the 

 silence of bird and insect life at sunrise. My own ex- 

 perience has always been that winged creatures of every 

 kind have been left behind long before the first thou- 

 sand feet were reached. The height at which the swift 

 is flying is surmounted with the first leap into space, 

 and even when sailing at the lowest levels compatible 

 with safety the skj'lark is neither seen or heard ; very 

 possibly, however, all creatures of the air take alarm at 

 a balloon and naturally give it a wide birth. 



Sounds claimed our closest attention throughout our 

 voyage, inasmuch as we were constantly straining our 

 ears to determine whether we were over land or sea 

 The deep cloud-barrier below us certainly appeared con- 

 ducive rather than inimical to the penetration of sound 

 from earth. At almost our highest elevation the bark 

 of a dog was caught, while the shrill challenge of many 

 cocks reached nearly as high. The bellow of cattle was 

 heard at upwards of 6,000 feet, the ringing of horses' 

 hoofs on a hard road at a thousand feet lower, and at 

 4,000 feet the unmistakable splashing of ducks on 

 water. The strangest case of great penetration how- 

 ever was afforded by the splash of waves on shore. I 

 would submit that our ears were highly strung and 

 abnormally sensitive to this sound, as being that which 

 we most dreaded to hear. 



One other sound of an uncanny nature there was 

 that began to haunt us as we reached the loftier 

 regions. Amid the dead silence we heard, fitfully, 

 stealthy footsteps as of someone walking softly outside 

 the car. 



When presently its cause was detected it proved to 

 be a sound of ill omen. It was the stretching of the 

 ropes vrnder the hot sun, and the silk giving out as the 

 gas continued to expand and send us mounting yet 

 higher. 



PLANTS AND THEIR FOOD. 



By H. H. W. Pearson, b.a. (Cantab.). 



As we observe the young wheat plants just appear- 

 ing above the ground, and in a few months' time see 

 the same plants, full-grown and almost ripe for harvest, 

 we cannot but wonder what has been the nature 

 of their food and whence they have obtained it. In 

 the case of animals, at least of the higher animals, 

 ordinary observation is sufficient to give us a good deal 

 of information respecting the nature and sources of the 

 food upon which they live. But no amount of obser- 

 vation will enable us to see anvthing of the nature of 

 food entering the wheat plants. We know that they 

 have roots in the ground, and can imagine that these 

 take something from the soil which the plants use as 

 food ; this, however, teaches us nothing, and we soon 

 realise that we must adopt some other method than 

 that of out-of-door observation before we can hope to 

 obtain the information which we seek. 



It is more than 2000 years since philosophers began 

 to speculate about the food of plants and what we may 

 term their " digestive " processes, but it is onlv during 

 the latter half of this century that really clear and 

 definite notions concerning the food supplies of the 

 vegetable world have been generally accepted bv scien- 

 tific men. 



Aristotle could find in plants nothing which might be 

 supposed 'o digest food materials in the same manner 

 as the stomach of an animal ; and he saw no trace of 

 any excrement or useless matter being cast off. He 

 therefore believed that no process corresponding to 

 digestion took place in plants. In order that this 

 might be possible he supposed that the food was not 

 only obtained from the earth, but was so prepared in 

 and by the soil that it could be taken up by the roots 

 and at once applied to the purposes of growth without 

 undergoing any further change. In other words the 

 soil not only supplied the food materials but also 

 digested them and yielded the products up to the roots 

 in such a condition that they could be at rnce added 1o 



