1894. ] | Anatomical and Physiological Researches. 409 
Investigations on pine and oak wood.? 
This series of investigations by Dr. R. Hartig, begun in 
1891 and completed early in the present year are a continua- 
tion of investigations begun many years ago; and they are to 
be followed by others by the same author dealing especially 
with the influences exerted by the soil in which trees grow, 
and the results obtained by growing ‘trees in masses and in 
theopen. While the investigations were conducted in accord- 
ance with scientific methods nothing that will be of value to 
the practical forester has been omitted. 
INE.—The trees studied were grouped in five or six classes 
according to diameter at a given height above the ground. 
or convenience periods of ten or twenty years are taken as- 
units, each designated as a growth period. Classes one, two, 
and three attained the maximum annual growth in height in the 
Stowth period between thirty and forty years; class four a dec- 
Ee eAtlicr; class five continued its qiax Hainan’ growth 
nearly twenty years, i. e., from twenty to forty. Class six 
did not reach its greatest growth until the two periods be- 
tween forty and sixty years. The last tree had early fallen 
hind the others in growth and was consequently overshad- 
owed by them. By the time the forest was forty years old 
class six was so completely shaded that a rapid growth in 
height became necessary in order to obtain sunlight. 
of 2 * pine tree one hundred years old five of the annual rings 
olay Within the last twenty years of growth, did not ex- 
Hi wn to a point 1.3 meters above the ground; four were 
"ahead at a point 3-5 meters above the ground; two at 5-5 , 
eae and one at 7.7 meters. Two of these short ee 
indicat. med more than ten years before the tree died. be 
F that he an exceedingly interesting physiological ae 29 ne 
- ing ite Cambium may remain inactive for years witho 
Power of cell-division. 
4 result of these and some earlier investigations the au- 
Bri ves his theory for the formation of the annual par : 
tated it is as follows: The wood formed in the ear 4 us 
Wide ‘ib irsg Season is composed chiefly of large — ae 2, 
Mis Rea These are designated as conducting vi ie 
- Stream § these that the larger portion of the transpt ae 
ay Passes. When a sufficient quantity of conducting ts" 
" eS Sa eres ers Zeitschrift. 1: 129, ae oe 
is * 49, 249, 289. 1893.—3: 1, 49, 172, 193. oe: 
of 
