12 MICROSCOPIC ANATOMY OF THE TEETH 



only say with Hutton, we find * no vestige of a beginning, 

 no prospect of an end \ l 



1 For an interesting description of Arrhenius' view of the mode by which 

 minute organic particles might be supposed to be disseminated into space 

 from our atmosphere, see Growth and Form, by D'Arcy W. Thompson, 

 pp. 48 and 49. It has, however, been suggested that the nature and 

 intensity of the light outside our atmosphere would be rapidly destructive 

 to all forms of life, and as Sir Ray Lankester says in a recent work (4) : 

 ' Hence Sir James Dewar argues that, whilst it would appear that the 

 extreme cold of space would not kill a minute living germ and prevent 

 it passing from planet to planet or from remotest space to our earth, 

 yet one thing which is more abundant in space than within the shell of our 

 atmosphere is absolutely destructive to such minute particles of living 

 matter, even when hard frozen, and that is intense light, the ultra-visible 

 vibrations of smallest wave length.' 



REFERENCES 



1. Bateson. MendeVs Principles of Heredity. Camb., 1909. 



2. Beddard, F. E. Camb. Nat. Hist., x. 43-4. 



3. Darwin, C. (a) Origin of Species, p. 282 ; (6) ibid., p. 292. 



4. Lankester, E. R. Diversions of a Naturalist, p. 159. 



5. Mendel, Gregor Johann. Versuche uber Pflanzen-Hybriden : Verb. 

 Naturf. Ver. in Brunn, Bd. 10, 1865. Translation in Journal Roy. 

 Horticult. Soc., 1901, xxv, xxvi. 



6. Rose, C. ' liber die Zahnleiste und die Eischwiele der Sauropsiden.' 

 Anat. Anzeig., 1892, Xos. 23 and 24, p. 749. 



7. Thompson, D'Arcy W. Growth ami Form. Camb., 1917. 



8. De Vries, Hugo. Plant Breeding, London, 1907, p. 3. 



9. Wilson, E. B. The Cell in Development and Inheritance. London and 

 New York, 1896. 



