SEEDLINGS, FOODSTORES AND GERMINATION. 73 



a sort of nervous union, it is difficult to explain these 

 connections. 



The protoplasm of a plant cell is poisoned by many 

 of those substances which are fatal to man. Cells may 

 be chloroformed or killed by ether or by alcohol. Yeast 

 cells are rather stimulated than otherwise by a slight 

 proportion of alcohol, but the presence of from 10-15 

 per cent, of alcohol in the solution kills them. Every 

 cell also has to breathe in order to keep alive : it takes 

 in oxygen and gives out carbonic acid gas. It has the 

 power of secreting or forming materials of the most 

 diverse kinds from the fluid in which it lives ; it is in 

 fact by this secretion of substances with the qualities 

 desired for any particular purpose that most of the life- 

 work of the cell is fulfilled. The feeding of a plant cell 

 is, however, carried on in quite a different way to that 

 of an animal, though the actual material of vegetable- 

 protoplasm does not differ from that in the animal body. 

 The protoplasm always consists of carbon, hydrogen, 

 oxygen, nitrogen, sulphur, and often also of phosphorus. 

 It is impossible to give a chemical formula for protoplasm, 

 because it cannot be analysed without killing it, and 

 when dead, it is no longer protoplasm. The necessities 

 of life for a vegetable may be roughly summed up as 

 follows : 



1. It breathes (takes in oxygen and gives out carbonic 

 acid). 



2. It absorbs water and, dissolved in the water, 

 nitrogen, sulphur and phosphorus which it requires for 

 its protoplasm. Other minerals of great importance are 

 also absorbed in the water. 



3. It obtains carbonic acid gas from the atmosphere. 



4. It obtains energy from the sunlight. 



5. It requires mechanical support. 



