158 THE LIFE OF THE PLANT 



These are the bundles, and they are either long and 

 straight, running parallel to one another, or they inter- 

 lace in a complicated fashion, forming a network of which 

 only a faint idea is obtained on simply glancing at the 

 leaf. In order to realise the thinness and delicacy of 

 this network, we have only to let the leaf rot in water 

 for some time ; then we shall be able without difficulty 

 to remove with a soft brush both the epidermis and the 

 fundamental tissue of the leaf, and separate this network 

 of nerves, to which no lace can be compared for delicacy. 1 

 The name i nerves ' is not very happily chosen, since 

 these organs have almost nothing in common with the 

 nerves of animals. If any analogy is necessary it would 

 be more appropriate to compare them to a skeleton and 

 a vascular system combined, since they form the hard 

 skeleton of the leaf, and also a system of canals for the 

 translocation of nutrient substances. I have expressed 

 myself rather carefully in saying that they have almost 

 nothing in common with the nerves of animals; because, 

 as we shall see, there is a theory that they are the paths 

 by which irritation is transmitted in the plant. If this 

 theory be confirmed we shall evidently have to recognise 

 in them a certain, though remote, resemblance to the 

 nerves of animals. 



The same nerves or veins so apparent in the leaf 

 extend also into the stem, where they are less sharply 

 defined, and do not strike the eye in the same way. 

 Different plants, however, present a very different 

 structure in this respect. Let us examine two very 

 common examples. In the monocotyledonous 2 class 

 of plants, to which for instance our cereals, asparagus, 

 and palms belong, these bundles are scattered in the 

 fundamental tissue as is shown in the transverse section 

 of fig. 45, I. A longitudinal and transverse section of 



1 Other parts of the plant can be treated in the same way, and then 

 semi-transparent ' phantom ' bouquets, so to speak, can be made of them. 



2 So called on account of their possessing only one cotyledon. 



