1892. 



SOME NEW BOOKS. 631 



errors into which the writers have fallen make it quite necessary to 

 warn teachers about to consult books on manual instruction that 

 they should read the chapters on the growth and structure of trees 

 with much caution, or, better still, they should not read them at all. 

 The information which they require can best be obtained from a good 

 text-book on elementary botany, or from that capital book " The 

 Oak," by Marshall Ward. 



In illustration of our contention, we have selected the two recently 

 published works mentioned above. In each of these books we find 

 whole paragraphs incorrect in every detail, the writers having any- 

 thing but "clear ideas" of how a tree really grows, and what is the 

 true nature of the current of water which passes from the roots 

 upwards. The transpiration current, as such, is not mentioned, and 

 the true function of foliage-leaves, together with the distribution of the 

 plastic substances to all growing organs, is totally ignored. The 

 result of this year's examinations having just been published, it would 

 be interesting to know how many teachers who used these books 

 failed to express themselves clearly in answering questions on the 

 mode of growth of plants. 



In the first-mentioned work we note, on page 40 : " A slowly- 

 flowing current of sap, obtained principally by the roots, ascends the 

 tree, and the wood-forming materials contained in it feed and thicken 

 the walls of the tracheides." On the subject of felling we are told : 

 ■"A tree should always be felled when the sap is at a standstill — the 

 height of summer — when it has ceased to run up the tree, but has 

 not yet begun to return ; or the winter, when it has completely run 

 down " (page 44). 



From this the teacher of manual training is to obtain "clear 

 ideas," which he will hand on to his class. It is no great stretch of 

 the imagination to picture a boy going home from his lesson with a 

 confused notion that sap has a kind of clockwork action ; it 

 occasionally "runs down," and sometimes " stops." 



The following, from the second work, reads like a huge joke : 

 ^' The rising or common sap containing much moisture flows towards 

 the leaves. Oxygen and moisture are evaporated, while carbonic 

 acid is absorbed by means of the stomata. The sap, now changed 

 to proper sap, descends in the autumn towards the roots between 

 the bark and the stem, depositing new woody fibres in the cambium 

 (sticky substance) surrounding the stem. Thus, a new deposit of 

 woody matter is formed from the sap all round the stem." 



It is rather startling to be gravely told that the sap contains much 

 moisture, and that the proper sap descends in autumn after staying 

 up aloft for so long ! 



We trust that should a second edition of either of these hand- 

 books be called for (they are capital guides respecting the manual 

 instruction) the writers will see that the part dealing with the growth 

 and structure of trees is entirely re-written by persons competent to 

 deal with the subject. 



