METEORITES AND TEE ORIGIN OF LIFE. 



87 



der about through space may not also strew 

 germs of life where a new heavenly body has be- 

 come fitted to offer a habitat to organized creat- 

 ures ? " The hypothesis, in the form set forth 

 in 1871 by Prof. Helmholtz and Sir William 

 Thomson, was vigorously handled by Zollner, 

 of Leipsic, whose work, " Ueber die Natur der 

 Cometen," appeared in the following year. In 

 the Vorrede of his book he passes his countryman 

 by unmentioned, but declares Sir William Thom- 

 son's proposition to be unscientific, and that in a 

 twofold sense. In the first place he maintains it 

 is unscientific in a formal or logical sense, in that 

 it changes the original simple question, Why has 

 our earth become covered with organisms ? into 

 a second, Why had that heavenly body the frag- 

 ment of which fell upon our planet become cov- 

 ered with vegetation, and not our earth itself? 

 " If, however," he adds, " bearing in mind an 

 earlier dictum, 1 we regard inorganic and organic 

 matter as two substances from all eternity di- 

 verse, just as in accordance with our present 

 views we consider two chemical elements to be 

 diverse, such an hypothesis as that now advanced 

 must be at variance with the destructibility of 

 organisms by heat which experience has taught 

 us." 



"Again," contends Zollner, "the hypothesis 

 in its material bearing is unscientific. When a 

 meteorite plunges with planetary velocity into 

 our atmosphere, the loss of vis viva arising from 

 friction is converted into heat, which raises the 

 temperature of the stone to a point where incan- 

 descence and combustion take place. This, at all 

 events, is the theory at present generally held to 

 explain the phenomena of star-showers and fire- 

 balls. A meteorite, then, laden with organisms, 

 even if it could withstand the sundering of the 

 parent mass unscathed, and should take no part 

 in the general rise of temperature resulting from 

 this disruption, must of necessity traverse the 

 , earth's atmosphere before it could deliver at the 

 earth's surface organisms to stock our planet 

 with living forms." 2 



Helmholtz did not long delay in replying to 

 Zbllner's criticism on this question. An oppor- 

 tunity occurred during the publication, in the fol- 

 lowing year, 1873, of the second part of the Ger- 

 man translation of Thomson and Tait's " Hand- 

 book of Theoretical Physics." The preface con- 

 tains Helmholtz's answer. 3 He points to the fact, 



1 " Dead matter cannot become living matter unless it 

 be subject to the influence of matter already living." 



2 " Ueber die Natur der Cometen. Von J. C. F. Zoll- 

 ner." Leipzig: Engelmann, 1ST2, p. 2i. 



3 "Handbuch der theoretischen Physik. Von W. 



confirmed by numerous observers, that the larger 

 meteoric stones, during their transit through our 

 atmosphere, become heated only on the outer 

 surface, the interior remaining cold — often very 

 cold. Germs which may happen to lie in the 

 crevices of such stones would be protected from 

 scorching while traveling through the air. Those, 

 moreover, which lie on or near the surface of the 

 aerolite would, as soon as it entered the upper 

 and most attenuated strata of our atmosphere, 

 be blown off by the swift and violent current of 

 air long ere the stone can rend those denser 

 layers of our gaseous envelope where compres- 

 sion is sufficiently great to cause a perceptible 

 rise of temperature. As regards that other point 

 of debate, referred to by Thomson only, the col- 

 lision of two cosmical masses, Helmholtz shows 

 that the first result of contact would be violent 

 mechanical movement, and that it is only when 

 they begin to be worn down and destroyed by 

 friction that heat would be developed. It is not 

 known whether this may not continue for hours 

 or days, or even weeks. Such portions as at 

 the first, moment of contact are hurled away with 

 planetary velocity may consequently be driven 

 from the scene of action before any rise of tem- 

 perature may have taken place. " It is not im- 

 possible," he adds, " that a meteorite or a swarm 

 of meteorites, in traversing the upper layers 

 of the atmosphere of a heavenly body, may 

 either scatter from them or carry with them 

 a quantity of air containing unscorched germs. 

 These are possibilities which are not yet to be 

 taken as probabilities; they are questions which, 

 from the fact of their existence and range, are to 

 be kept in sight, so that, should a case arise, they 

 may receive an answer either by actual obser- 

 vations or by some conclusive deduction." It 

 should be mentioned here that these views of 

 Helmholtz's are also to be met with in a supple- 

 ment to his lecture on the origin of the solar sys- 

 tem. 



In tracing the gradual development of this 

 important controversy, we now arrive at the pres- 

 ent year, and proceed to discuss the allusion 

 made to it by Prof. Allen Thomson in his ad- 

 dress at Plymouth. The difficulty regarding the 

 origin of life is, he considers, not abolished, but 

 only removed to a more remote period, by the 

 supposition of the transport of germs from an- 

 other planet, or their introduction by means of 

 meteorites or meteoric dust ; for, besides the ob- 



Tbomson und P. G. Tait." TTebersetzung von H. Helm- 

 holtz und G. "Wertheim. Braunschweig: Vieweg unci 

 Sohn, 1874. Erster Band. Zweiter Theil. 11. 



