195 
containing the high proportion of insoluble mineral matter, which are 
very much like soil. Those containing high proportions of organic mat- 
ter vary in color from light brown to dark brown according to the per- 
centage of moisture they contain. As stated before, their physical con- 
dition, when air-dried, is excellent, both for handling and for application 
to the soil, and the analyses given above represent very fairly the aver- 
age composition of the material, which may be valued at from $15 to $55 
per ton, reckoning upon the basis for determination of the value of fer- 
tilizers adopted by Dr. Ch. A. Goessmann, inspector of fertilizers for the 
State of Massachusetts, in his report for 1876. These values compare 
favorably with those of the fish-products largely manufactured in New 
England, and even with Peruvian guano, analyses of both of which may 
be found in the report just alluded to. With these facts before us we 
may readily recognize the importance of the development of these de- 
posits in the South, where fertilizing materials are so much needed and 
are so costly, and especially is this true when they may be obtained 
from this source for the mere cost of remoyal. 
INFLUENCE OF LIME-SALTS IN PLANT-GROWTH.—Joseph Boehm has 
lately conducted a series of experiments to determine the value of lime- 
salts in the economy of plant-growth, and has found that its principal 
function appears to be that of furnishing nourishment for support of the 
development of the cell-walls, without: assisting in any way in the direct 
production of starch. According to the results obtained by other inves- 
tigators, the function of the formation of starch in the chlorophyl-grains 
must be delegated to potash. This latter function cannot, however, 
according to Boehm, be carried on in the absence of lime-salts, since 
plants grown in potassic chloride, carbonate, or phosphate alone grew 
no better than those to which only distilled water was supplied. Germi- 
nating plants will grow as long as they can obtain nourishment from the 
reserve stock of food in the parent seed, but it appears that the mineral 
elements become exhausted before the organic elements are all elaborated, 
and that, for complete development of the plauts, mineral matters must 
be added to the soil or solutions in which they are grown. Experiments 
with various alkaline salts, in absence of lime, proved them to be unable 
of themselves to supply the deficiency, and in many cases they were 
absolutely poisonous. This was found to be true of carbonate of mag- 
nesia, confirming the results of an investigation into the physiological 
action of magnesia, made in the laboratory of this Department. The 
poisonous action of magnesia-salts may, however, be neutralized by car- 
bonate of lime. 
But when the alkaline salts were applied in presence of lime, the growth 
was vigorous and healthy, and he therefore believes that lime-salts are 
as essential to the change of starch to sugar, &c., in building up 
cell-walls which constitute the skeleton of the plant, as it is in the animal 
economy in the metamorphosis of the cartilage of the bones. 
With regard to the value of potash, the author quotes from Nobbe 
that potash is essential to plant-growth, and that it is a condition of the 
formation of starch in the chlorophyl-grains. The chloride is considered 
the best form in which to apply it to the soil, and next to this compound 
the nitrate, while the sulphate and phosphate are considered positively 
injurious. ® 
From these statements it would therefore appear that the combination 
of lime-salts with potash-salts is the most favorable combination for 
the stimulation of the growth of plants. 
