322 



The Journal of Heredity 



the orbits of the smaller and the outer 

 planets. . . . The organism would 

 cross the orbit of Mars after twenty 

 days, the Jupiter orbit after eighty 

 days, and the orbit of Neptune after 

 fourteen months. Our nearest solar 

 system would be reached in 9,000 years." 



LIFE FROM OTHER WORLDS 



There would, therefore, be no difli- 

 culty of time about transferring life 

 from one planet of our system to an- 

 other, for almost any germ could live 

 that long. But if life is to be considered 

 eternal, it must be capable of trans- 

 mission from one solar system to 

 another, and the shortest trip to ours 

 is, as noted, 9,000 years. Could any 

 known organism survive so long? 

 Arrhenius thinks it could because of the 

 low temperature (below — 200° C.) of the 

 space through which it would travel, 

 where no chemical reaction could take 

 place, and hence no decomposition or 

 deterioration in the spores ; and because 

 of the absence of water vapor. There 

 is even experimental evidence to support 

 this. Bacteria were exposed for six 

 months to liquid air, at a temperature 

 of about —190° C. and their vitality 

 did not seem to be affected in any way. 

 In the cosmic space the temperature is 

 lower than this, there is no atmos])here 

 or water vapor and, says Dr. Loeb, 

 "there is hence no reason why spores 

 should lose appreciably more of their 

 germinating power in 10,000 years 

 than in six months. We must, there- 

 fore, admit the possibility that spores 

 may move for an almost infinite length 

 of time through cosmic space and yet 

 be ready for germination when they 

 fall upon a planet in which all the 

 conditions for germination and develop- 

 ment exist, e. g., water, proi^er temi^era- 

 ture, and the right nutritive substances 

 dissolved in the water (inclusive of free 

 oxygen)." 



it is thus possible to imagine that 

 living matter never had a beginning, 

 any more than matter in general. If 

 so, it would be idle to try to create life 

 in the lal)()ratory. But it is still neces- 

 sary to inquire more closeh', how living 



matter differs from dead matter. How 

 does the growth of a germ differ from 

 the growth of a crystal? The essential 

 difference is that the crystal simply 

 adds to itself by taking up material 

 like itself, while the living cell adds to 

 itself by building up compounds, speci- 

 fic for each organism, from the dilute, 

 split products of these compounds. 

 The one process is probably just as much 

 explicable in chemical terms as the 

 other. While the life process is 

 ■^^stly more complicated, and also 

 differs in kind from such a simple 

 chemical process as the manufacture 

 of rock candy, yet it is not necessary, 

 in Dr. Loeb's view, to regard the latter 

 as wholly natural and the former as 

 partly supernatural. 



WHAT IS A SPECIES? 



2. The second point in which Dr. 

 Loeb attempts to substitute a simple 

 mechanical idea for a mystical one, is 

 in the explanation of the basis of a 

 species. Under the microscope, the 

 protoplasm from the cell which will 

 produce a whale, can not be told from 

 the proto])lasm which would produce 

 a hummingbird. Yet whale eggs al- 

 ways give rise to whales, and humming- 

 bird eggs to hummingbirds. Further- 

 more, a species may remain constant 

 for a long time. Walcott has found 

 fossils of annelids, snails, crustaceans 

 and algae in precambrian rocks in 

 British Columbia, whose age mav be 

 as great as 200,000,000 years; yet these 

 are so closely related to forms existing 

 today that scientists have no difficulty 

 in finding the genus among modern 

 forms to which each of the fossils be- 

 longs. Wheeler has studied ants i^re- 

 served in amlx-r for 2.000.000 years, 

 which belong to species that are still 

 living. And the constancy of the sea 

 iincTtc'brate, Lingula, for at least 

 100,000,000 years, was recently illus- 

 trated in this Journal.'^ Moreover, 

 the ge;ieticist knows that species which 

 are widely different from each other 

 cannot be hybridized. They are "in- 

 com])atil)le." What is it that under- 

 lies this specificity? 



2 "The r)l(k-st Known Animal." JorKNAi. ov IIi-kkditv. VTTT. p. 146, Ajnil, 1017. 



