NOTES AND ABSTRACTS. 
513 
sp. which occurs on lettuce, celery, &c, known as S. Libertiana, the latter to 
Sclerotinia Panaris, which cultivation proves to be identical with 5. Smilacina, 
which also occurs on Smilacina racemosa. The lesions produced on the two hosts 
are identical. — F. J. C. 
Seed Sterilizer, Calcium Hypochlorite as a. By James K. Wilson (Amer. 
Jour. Bot. vol. ii. No. 8, Oct. 1915, pp. 420-427). — For many physiological ex- 
periments, seeds and seedlings free from bacteria and fungus spores are necessary. 
Numerous disinfectants have been tried from time to time by many investigators, 
with but indifferent results. The author has tried mercuric chloride, alcohol, 
formalin, hydrogen peroxide, and combinations of these substances, but has 
found them to be unsatisfactory. He now recommends calcium hypochlorite 
(bleaching powder), used in the following manner : 10 grams of commercial 
chloride of lime (with 28 per cent, available chlorine) is mixed with 140 cc. of 
water. The mixture is allowed to settle for fen minutes and the liquid decanted 
off or filtered. The filtrate, containing about 2 per cent, chlorine, is used as the 
disinfectant. Dilutions from this strength as well as the full strength may be 
used in the proportion of five volumes of the solution to one volume of the seed. 
The time required for sterilizing the seeds varied from four hours to twenty-four 
hours ; if left over this period, injury to seeds was caused. Satisfactory steriliza- 
tion was secured in every case with the exception of vetch seed, while in the 
case of seedlings this sterilization was maintained over a period of thirty days 
or more, and demonstrated the efficiency of this method as a means of securing 
sterile seedlings. It is also of service in eradicating such plant diseases as may 
be controlled by treating the seed. It is suggested by Hooker that this effect 
is probably due to the hypochlorous acid which acts as the toxic agent. There 
is appended a short bibliography, giving references to previous work in this 
subject of seed sterilization. — A. B. 
Seeds, Mechanics of Dormancy in. By Wm. Crocker (Amer, Jour. Bot. 
vol. iii. No. 3, March 1916, pp. 99-120). — Dormancy in plants is common in 
three organs, seeds, spores, and buds. That in seeds has been studied in detail 
by the author, who arrives at the following conclusions : — 
Dormancy in seeds results generally from the inhibition of one or more of 
the processes preceding or accompanying germination. The problems are 
becoming questions of the conditions for growth of the embryo, and the funda- 
mental changes occurring in the embryo at the beginning of germination ; as 
well as of a study of the physical characters (permeability and breaking 
strength) of the colloids of the seed-coats as affected by age, various conditions, 
and reagents. 
Seed-coats play an important rdle in primary and secondary dormancy. 
Often they are of such a colloidal nature as to be modified by even very low 
concentrations of reagents. In the past, such results have been interpreted 
wrongly as stimulus responses. 
Regarding conditions of germination of seeds, the recent trend is towards 
the need of certain general physical conditions and away from the need of specific 
chemical stimuli. 
After-ripening of seeds may involve growth of a rudimentary embryo, funda- 
mental chemical changes in an otherwise mature embryo, or chemical changes 
in the seed-coats. In after-ripening there is often a complex interrelation 
between coat and embryo changes. — A, B. 
Senile Changes in Leaves of Vitis vulpina L., and certain other Plants. By 
H. M. Benedict (U.S.A. Exp. Sin., Cornell, Mem. No. 7, pp. 281-370, 1915). 
" An attempt to answer the question whether general progressive age-changes 
occur during the vegetative life of a woody perennial." The author's observa- 
tions concern primarily the size of the aggregations of photosynthetically active 
cells, the vein islets in the meshes of the network of veinlets, or in other words 
the size of the meshes. The results of his observations show that " The size of 
the vein islets remains constant, if of the same age. The areas and thickness of 
the leaves show more variation than the minimum and maximum areas of the 
vein islets in different leaves of the same plant. The size of the vein islets is 
greatest in the youngest leaves, and undergoes a progressive decrease with 
advancing age. Other age-changes determined in the leaves of Vitis are decrease 
in rate of CO a production, decrease in imbibition of water by powdered leaves, 
decrease in acidity, increase in number and decrease in size of stomata, and 
probably a decrease in size of palisade cells and an increase in the proportion of 
cytoplasm to nucleus." — G. H. 
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