306 



The Museum Gazette 



In two splendid specimens of the Australian Giant Crab 

 the right claw is very much larger than the left. (See Crus- 

 tacean Department, British Museum, left hand on entering.) 



Note on the Growth of Trees. 



We quote the following paragraph from some interesting 

 notes upon the exhibits in the Forestry Section at the 

 Nuremberg Exhibition of Bavarian industries, which are 

 given in the October issue of the Journal of the Board of 

 Agriculture : — 



il A number of cross-sections exhibit the inexplicable condition of 

 things that growth is more rapid on the under side than on the upper 

 side of the branch of a conifer, whereas in the branch of a dicotyledon 

 the opposite is the case. This may be seen by cutting off horizontal 

 branches of the two classes of trees named. In the case of the 

 conifer, the pith will be found to be nearer the upper than the lower 

 side of the section, while in the dicotyledon, the shortest radius is on 

 the under side. The horizontally disposed roots of trees (the spruce is 

 a good example) also show marked eccentric growth, but in their case 

 the character of the eccentricity is always the same, the greatest 

 growth, and therefore the longest radius, being on the upper side. It 

 is evident that the upper side of a root is subjected to less pressure 

 from the soil than the lower side, and as the cambium makes most 

 wood where the pressure is least, the greatest growth is found in a 

 root precisely where it is to be expected. But the variable condition 

 of things in the branches of conifers and dicotyledons has always been 

 a puzzle to botanists, and no satisfactory explanation is yet available. 

 Nor is it quite easy to say why, in a tree grown on a steep hillside, 

 greater growth should be on the side away from the hill." 



Larch Trees and Saw-flies. 



A species of saw-fly, hitherto not observed in large numbers 

 in this country, has appeared in a larch plantation in Cumber- 

 land ; its larvae have been sufficiently abundant to seriously 

 damage the plantation, which is stated to be a large one. It 

 is the Nematus erichsonii of Hartmann, and is of wide dis- 

 tribution in Europe. In this country it has occurred at 

 Glanvilles Wootton, near Esher, Wye, Great Staughton and 

 Budleigh Salterton, but without doing material damage. 

 Hagen has recorded it from the United States. At maturity 



