330 



observable in the colour of the bark, its corkiness, and its thickness, 

 the colour, shape and size of the leaves, the number of glands^on the 

 petiole, the time when fruiting begins, the number of seeds in the 

 fruit, their shape, size and colour, and lastlj' of the greatest 

 importance in the amount of latex. On p. 63 the authors recom- 

 mend the collection of seeds from wild trees found to yield well ; from 

 p. 42 forward the way in which the Brazilian seringueiro taps is 

 described, the conclusion being reached that the better "to avoid 

 damage to state property resulting from bad tapping, it will suffice to . 

 increase the control of the work of the seringueiro instead of as 

 Akers advised enforcing the disuse of his tapping axe in favour of a 

 tapping implement more modern but strange among the Amazon 

 workmen.'' 



What the authors say about the endebtedness of the seringueiro 

 to the middlemen exposes the weakest spot in the industry of Brazil. 



After dealing with Hevea, the authors discuss Manihot. Of 

 species several are defined including a new one Manihot Toledi ; and 

 as regards them the conclusion is reached that generally it is best to 

 plant M. Glaziovii, if it is a case of planting a Manihot, although 

 of the smaller species M. Jieptaphylla and M. piaiihyensis for instance 

 might be planted, or M. Toledi which is intermediate in size. 



The authors give a series of facts showing that about two centres 

 in Brazil, Ceara rubber planting is taking a hold. They add that the 

 wild plant has received such severe treatment that it no longer 

 counts as a reliable source of commercial rubber. 



The establishment of an experimental station to select, improve 

 a nd experiment with Ceara rubber is set forth as desirable. 



The last few pages of the book are devoted to a discussion of 

 Castilloa Ulei and Hancomia speciosa. 



Annual Report of the Board of Scientific Advice for India for the 

 year 1913-14 (Calcutta, 1915). Among the records in this report of 

 extensive work done, a few are of special interest in Malaya. In the 

 report for 1912-13 it had been explained how in the soil of swampy 

 paddy lands various gases are product d, notably methane or marsh- 

 gas, nitrogen, hydrogen and carbonic-acid gas; and that after the 

 paddy has been planted out a film forms on the surface consisting 

 largely of bacteria, and minute green organisms such as algae and 

 diatoms. Messrs. W. H. Harrison and Subramania Aiyar, continu- 

 ing their work, show (page 9) how this film lives on the gases that 

 exist as a result of changes within the soil and doubtless are in con- 

 tinual process of formation, using up the methane-and the carbonic- 

 acid gas (in part at any rate) with a liberation therefrom of oxygen. 

 The function of this surface film is thus to liberate oxygen, so that 

 the rice roots are more liberally aerated than they would be without it. 

 Drainage of rice land by producing a flow of water through the film 

 into the soil carries this oxygen to the rice roots below; but as too 



