290 NATURE STUDY AND AGRICULTURE 



the egg and examine the lower part. Does it seem to have 

 anything more in it than when you placed it on the bottle? 

 The fact is that water has passed through the membrane 

 into the egg. So much has gone in that some of the white 

 of egg has been pushed up into the tube. The process by 

 which liquids or gases pass through animal or plant mem- 

 brane is called osmosis. 



This process may be shown in another way. Have a 

 butcher remove a piece of the thin membrane from a leg 

 of lamb or mutton, or when butchering time comes have 

 some of the pupils save the skin or pericardium that sur- 

 rounds a pig's heart. You can spread this out, dry it, 

 and keep it any length of time. Tie a piece of this mem- 

 brane over the large end of a student's lamp chimney, 

 moistening it thoroughly, first by soaking in a little warm, 

 soapy water. Fill a tumbler two-thirds full of water 

 colored with red ink. Place in the lamp chimney a little 

 clear water so it will stand about an inch and a half from 

 the bottom. Now hang the chimney so it will rest in the 

 colored water. Set aside for a few hours and then note 

 what has taken place. Has any water passed into the 

 chimney through the membrane? Instead of water in 

 the chimney place some thick syrup and hang it in the 

 water. 



How do these experiments show what is taking place 

 in the soil between the water and the root hairs? The 

 walls of the root hairs are very thin and by osmosis the soil 

 water with the plant materials passes readily through 

 them. At the same time it is probable that a little of 

 the thicker substance in the root hairs passes out into the 

 soil. 



