clxxxviii Journal of the Asiatic Society of Bengal. [N.S., XIII, 



3. Importance of a detailed study of wild species with reference to 

 (a) economic questions and (b) the problem of the origin of species, as in- 

 dicated by a study of this genus. 



The Method of Inheritance of certain Characters in Rice. — By 



F. R. Parnell. 



This is a continuation of a paper given at the Science Congress in 



Madras two years ago. 



Certain characters, there described as simply dominant, are now seen 

 to be due to two factors. At least four factors are concerned in the vari- 

 ous types of awning investigated. 



Several types of gametic re-duplication were illustrated. These in- 

 clude two cases of coupling of separate factors giving a result which was 

 previously regarded as the effect of one factor on several organs. 



The Economic Significance of the Root-Development of Agri- 

 cultural Crops. 1 — By Albert Howard, and Gabrielle 

 L. C. Howard. 



The detailed study of the root-systems of the various agricultural 

 crops has been greatly neglected in the past. Hitherto far too much at- 

 tention has been devoted to the above ground portion of the plant and 

 it has almost been forgotten that a very large part of any crop consist- 

 of the root-system which is ordinarily out of sight This omission to 

 study the relation between the soil and the distribution of the roots is a 

 common feature of the variety trials which nowadays form so large a 

 part of Experiment Station work. 



The object of this paper is to show that a comparative study of the 

 root-systems of a set of varieties throws a considerable amount of light on 

 the relations which exist between the most suitable type of crop and the 



oil in which it grows. The results of variety trials often become con- 



iderably clearer from a study of the roots of the various varieties tried. 



For proper root development, one of the conditions necessary is good 

 soil aeration. Now in the alluvium of the plains of India one of the most 

 difficult things is to manage the soil so that its aeration is not interfered 

 with by rain or by irrigation water. The crumb structure of fine alluvial 



oils which is so easy to produce is also readily lost under monsoon and irri- 

 gation conditions. In consequence, the soil and the roots of the crops can- 

 not obtain sufficient oxygen and in many cases carbon dioxide accumulates 

 The crops suffer from lack of aeration in the soil and oxvgen becomes a 

 limiting factor. This is the explanation we have suggested for a whole 



enes of phenomena relating to crops on the Indo Gauge tic alluvium. 

 All the facts so far obtained fit into our aeration theory and we have 

 come to regard the surface layer of the Bihar alluvium as a vast oxygen 

 filter separating the atmosphere from the sub-soil water, which analysis 

 •shows is particularly poor in dissolved oxygen. All soil-aerating agencies 

 like surface-drainage at once increase production provided the supply of 

 organic matter in the soil is adequate. Now if this is true and if the Bihar 

 alluvium does act as an oxygen filter we should expect to find that all 

 the varieties which really thrive during the monsoon phase in this tract 

 are surface rooted and that very deep rooting kinds would not do well, 

 lo some extent, a similar rule ought to hold in the cold weather (rabi) 

 crops but not to quite the same extent as in these crops the rainfall be- 

 tween sowing time and harvest is small and during this period soil-aera- 



