HORIZONTAL DIFFUSION 



Values for C and ;// calculated from various spore-dispersal tests are 

 sho\Mi in Table VIII. Evidently for microbiological work we must use 

 high values of C^., perhaps because we are concerned with longer sampling 

 periods than Sutton. \Xt shall therefore choose Cy = o-8 (metre)*, and 

 Q = 0-12 (metre)*, as standard in Chapter XIII where deposition 

 gradients are considered in detail. There seems to be little in favour, 

 however, of adopting m = 2-0 instead of m = 1-75. 



TABLE VIII 



OBSERVED VALUES OF PARAMETERS IN SUTTON's DIFFUSION EQUATION FROM 

 EXPERIMENTS ON SPORE DISPERSAL 



Stepanov, 1935 

 Tilletia spores I 

 Tilletia spores II 

 Bovista spores 



Wilson & Baker, 1946 

 Lycopodium spores 

 Wind speed 17 metres/sec. 

 27 

 3-2 

 4-6 

 (mean of 7 experiments) 

 Gregory, Longhurst & 

 Sreeramulu {unpublished) 

 Lycopodium spores 



Wind speed 04 metres/sec. 

 1-05 

 1-28 

 1-63 

 264 

 Gregory {unpublished) 

 Lycopodium spores 



Cz 



vertical 

 (metre)7^ 



0-20 



o-ii 



0-22 



0-12 

 015 



Cy 



horizontal 

 (metre)V^ 



1-67 



0-35 

 0-89 



0-66 

 4-26^ 

 0-30 

 0-40 



0-97 

 0-28 

 0-58 

 089 

 1-40 



0-68 

 026 



1-49 

 1-90 

 165 



170 1-51 



1-97 0-88* 



175 1-64 



1-86 174 



1-92 — 



1-80 



212 



I 99 

 1-66 

 171 



1-98 

 1-94 



* abnormal values. 



Comparison of Theories of W. Schmidt ant) Sutton 



According to Schmidt's theory, a^ = sAt/p, so, because t = x/u, we 

 have log a = Mog X + i log {ikjpu). If this relation holds true in field 

 tests, plotting experimental data for log a against log x should give a line 



55 



