156 BOTANICAL GAZETTE [AuGusT 
of “biologic forms;” the other, called “generalizing factors,” bridging these 
differences and causing “‘the separate streams of evolving ‘biologic forms’ to flow 
into each other.” It is thought that these facts may explain the sudden appear- 
ance of a parasitic disease on plants which had hitherto proved immune.— 
BM, 
2 
Duvet?’ has been investigating, since 1899, the causes affecting the vitality — 
of seeds, with special reference to the conditions under which they are stored 
commercially. The general method pursued has been to store seed experimentally 
under all sorts of conditions, and afterward to ascertain the exact percentage of 
germination. The first factors determining the vitality of a seed are maturity, 
weather conditions at the time of harvesting (damp weather lowering the vitality), 
and methods of harvesting and curing (especially avoiding excessive heating). 
The life-period of a seed that has met these favorable conditions depends on 
environment, but the average life varies greatly in different families, genera, oF 
even species. There is no relation between the longevity of plants and the 
viable period of the seeds they produce. With proper precautions, the life of 
seeds may be greatly prolonged beyond the present record, and in co - 
handling moisture is the chief factor in shortening it. It seems that seeds can 
endure any degree of drying without injury, and that such a reduction in sid 
water content is necessary if vitality is to be preserved for a long period of yeats. 
It is said that “respiration” is not necessary to the life of a seed, and that the 
evidence goes to show that it “is not dependent on the preservation of the ee 
ticular ferment involved or on the zymogenic substance giving rise to the ne 
“The one important factor governing the longevity of good seed is dryméss: 
—~) MC. 
S. M. Courter?’ has published a preliminary account of his investigation 
of swamps. The paper is intended to collect and group together the facts con- 
cerning the swamp areas investigated as a basis for a future study of the problems 
involved. The data have been obtained from field studies extending ine 
three years and including swamps of six types: (1) a drained at Be 
Crooked River, in the northern part of the lower peninsula of Michigan; (2) 
undrained tamarack and black spruce swamp on North Manitou Island, pe 
Michigan; (3) a slowly drained arbor vitae swamp on the same island; — 
small, swampy lakes south of Chicago; (5) Horseshoe Lake, an old “ox 
cut off from the Mississippi River in southwestern Illinois; and (6) @ ac 
tupelo gum swamp in northeastern Arkansas. The discussion of gt 
consists of a description of the present topographical condition of . ‘ In 
together with a Summary of the principal plant forms that characterize ane 
Short, the paper is a brief comparison of certain widely separated swamp ©” 
Se een 96. Bull. 58: 
” 
7 Duvet, J. W. T., The vitality and germination of seeds, PP: 
Bur. = Industry, U. S. Dept. Agric. May 28, 1904. typical swam? 
° COULTER, SAMUEL Monps, An ecological comparison of some 
areas. Rep. Mo. Bot. Gard. 15:39-71. pls. 2g. 1904. 
mee 
