22 THE JOURNAL OF INDIAN BOTANY. 



With Spinifex squarrosus no tubular sheath is formed, for the 

 secretion does not cause the sand particles to adhere. It appears to 

 act rather as a lubricant or perhaps as a resisting layer to protect the 

 piliferous layer from damage by sharp grains of sand. Spinifex is not 

 related closely to any of the grasses noted by Price as possessing the 

 mucilage layer. The genus consists of only four species, occurring on 

 sandy shores of India, Malaya and N. Australia. 



The Water-supply, 



Every one knows that sand a very few inches below the surface 

 is damp, as also is any ordinary soil. With ordinary clay or loamy 

 soil this is usually taken to be due to an upward movement from low 

 levels of water drawn up by capillarity through the fine cracks 

 developed by the drying of the soil. This water being continually 

 dried at the surface of the ground. There may be a slow upward 

 movement of water also through sand ; but it is very slow. This 

 was determined by us both in the laboratory and in the sand of the 

 beach. In the laboratory two wide glass tubes were filled with dry 

 sand, the lower end closed with muslin and the tubes supported with 

 their lower ends, one in fresh water, the other in salt water. At 

 first the rise of water as shown by the darkening in colour of the 

 sand was rapid, but after the first day the rate fell off and after seven 

 days the level was practically stationary at 24 cms ; a slow rise went 

 on for several days till it reached 30 cms. Then no further rise was 

 noted. There was no appreciable difference between the two tubes. 

 The experiment was continued for 4| months without any change in 

 the level of the dampness being seen. It came to an end with the 

 rotting of the muslin holding in the sand. 



In another series of experiments 8-inch drain pipes were sunk 

 in sand in an enclosed space but open to the air. The pipes were 36 

 inches long. They were filled with dry sand, and some left open, 

 others closed at the top. No appreciable rise of water could be 

 detected after periods of three to six weeks except in one case where 

 the sand had a musty smell and was slightly more damp below than 

 above, pointing to a rise of water from below. Heavy rain had fallen 

 and the sand outside had been saturated, so that the water might 

 have come up as much by hydrostatic pressure as by capillarity.* 



• The use of pipes in this way has been objected to by Olsson-Seffer (1) 

 on the ground that no lateral movement of the air enclosed in the pipe is 

 possible as would, he considers, occur in nature, and that the free movement 

 of the water would be prejudiced thereby. But a little consideration would 

 show that in a homogeneous medium of practically limitless extent (as the 

 sands of the seashore) there can be no balance of lateral air-movement 

 inwards or outwards from any imagined volume, and that it is therefore per- 



