HOW PLANTS EAT. 49 



weeds; and above these again come other and 

 rather higher plants, in which the cellular tissue 

 assumes the form of a flat and leaf-like blade, as 

 in many broad sea-weeds. None of these, how- 

 ever, are called leaves in the strict sense, because 

 they consist of cells alone, without any ribs or 

 supporting framework. The higher types, how- 

 ever, like ferns and flowering plants, have such 

 ribs or frameworks, made of that stiffer and 

 tougher material called vascular tissue. This is 

 the most general distinction that exists between 

 plants ; the higher ones are known as Vascular 

 Plants, including all those with true leaves, such 

 as the common trees, herbs, and shrubs, and the 

 ferns and grasses in fact, almost all the things 

 ever thought of as plants by most ordinary ob- 

 servers ; the lower ones are known as Cellular 

 Plants, and include the kinds without true leaves 

 or vascular tissue, such as the seaweeds, fungi, 

 and microscopic plants only recognised as a rule 

 by botanical students. 



The higher plants, then, have for the most 

 part special organs, the leaves, told off to do 

 work for them as mouths and stomachs; while 

 other organs are told off to do other special work 

 of their own as the roots to drink, the flowers to 

 reproduce, the fruit and seeds to carry on the life 

 of the species to other generations, and so forth, 

 down to the hairs that protect the surface, or the 

 glands that produce honey to attract the fertilis- 

 ing insects. To the end, however, all parts of the 

 plant retain the power to eat carbonic acid, if 

 necessary ; so that many higher plants have no 

 true leaves, but use portions of the stem or 

 branches for the purpose of feeding. Any part 

 of the plant which contains the active living 

 4 



