1886-87.] Monthly Increase in Girth of Trees. 61 



able to the family of oaks, as nearly all the specimens under 

 observation grew very slowly. This curious halting in their 

 course, therefore, may be abnormal, although it is fair to state 

 that it occurred also in the healthy and vigorous Spanish 

 chestnut. On the other hand, the progress of the evergreens 

 was more regular. Abies Loiviana was the only species 

 which lagged in its course, ha\dng dropped from 28 per 

 cent, in May to 19 per cent, in June, rising again to 22 per 

 cent, in July. The Deodar was remarkable for its steady 

 progress to a maximum so late in the year as August. 



3. The spread of the increase over the months varied 

 very much in the different species. In two of the deciduous 

 group, — the lime and birch, — more than one-half of the 

 annual increase took place in the single month of July, and 

 in neither of them was there any increment in April or May 

 in any of the four years; but the very slow rate of increase 

 in these trees renders it doubtful whether so strange a result 

 is normal. On the other hand, the substantial growth of 

 the beech and Hungary oak w^as spread over June, July, 

 and August. On the whole, the increment of the evergreens 

 was more equally diffused over the months than that of the 

 deciduous group. No evergreen species grew more than 

 39 per cent, of its annual increase in a single month, and 

 there was no instance among them of an absolute deficiency 

 of increment in ]\Iay in any year, or in April for every year 

 of the four under observation. 



4- I expected to find that increase in girth would go on pari 

 passu with development of the leaf, but such was not by any 

 means invariably the case. This is shown in a rough way 

 in the Table, page 57. If we take, for example, the growth of 

 the Hungary oaks for April, which may be regarded as the 

 month of budding, and for May, which may be regarded as 

 the month of expansion, we find that the amount was nearly 

 equal, and similarly in the case of the sycamores that the 

 amount was actually greater in April than in May. The 

 results in the sycamores, indeed, are inconclusive, as their 

 very slow growth indicates a great lack of vigour ; but as to 

 the Hungary oaks there can scarcely be a mistake, as they are 

 the earliest and quickest growers on my list. But the proof is 

 strengthened if we consider the actual state of the foliage, — 

 which was carefully noted by me, — in connection with the 



