MISCELLANY. 



509 



minute coin-like bodies which are very abun- 

 dant in some coals, and which had been pre- 

 viously noticed by Witham, Dawson, and 

 others. The larger of these bodies Huxley 

 regarded as spore-cases, and the smaller as 

 spores, while he considered that their dis- 

 integration had led in most cases to the 

 formation of the bulk of what we call coal. 



Prof. Williamson showed in detail that 

 these were not spore-cases, but two kinds 

 of spores — microspores and macrospores — 

 such as severally occur in the upper and 

 lower portions of the fruits of many living 

 club-mosses. Their siz"es and structure de- 

 monstrate the truth of this conclusion, which 

 is further sustained by the fact that spore- 

 cases are not deciduous, but spores are; 

 and these objects, having fallen in such vast 

 myriads from gigantic club-mosses, can on- 

 ly have been deciduous organs. The lect- 

 urer then gave reasons for concluding that 

 these spores had played a much more limited 

 part in the origin of coal than Huxley had 

 assigned to them. According to Huxley, 

 coal is composed of mineral charcoal and 

 coal proper — the latter term being equiva- 

 lent to spores altered or unaltered. Prof. 

 Williamson, on the other hand, recognized 

 three such elements : mineral charcoal, that 

 is, fragments of fossil wood retaining its 

 structure; coal proper, that is, mineral char- 

 coal disorganized; and spores in various 

 states. 



We now distinguish in coal three groups 

 of fossil plants : 1. Those of which we have 

 the form but not the organization : 2. Those 

 of which we have both form and organiza- 

 tion ; 3. Those of which we know the struct- 

 ure, but are ignorant of the outward form. 

 What has yet to be done is the correlation 

 of the first and last of these three groups. 

 Brogniart long ago showed that most of the 

 coal-plants were cryptogamic — chiefly cala- 

 mites (allied to living horse-tails); lepido- 

 dendra (represented by the club-mosses) ; 

 ferns, and plants supposed to represent 

 pines and firs of the group known as gym- 

 nospermous exogens. 



Leached Ashes as a Fertilizer. — In a 



report to the Connecticut State Board of 

 Agriculture, Prof. S. W. Johnson gives the 

 results of some analyses made by himself 

 of specimens of leached ashes used for fertil- 



izing purposes. By these analyses leached 

 ashes are found to contain : less than one 

 per cent, of potash ; a large proportion of 

 water (not less than 35 per cent.) ; consider- 

 able sand or soil, and unburned coal, amount- 

 ing to from 6 to 15 per cent., when not in- 

 tentionally or largely adulterated ; about 45 

 per cent, carbonate of lime, which is the 

 chief fertilizing element in leached ashes ; a 

 little more than 1 per cent, of phosphoric 

 acid, and 3 to 4. per cent, of magnesia. 

 They contain no nitrates, but the carbonate 

 of lime in them favors the development of 

 nitrates when they are incorporated with 

 the soil, especially in conjunction with ani- 

 mal manures. 



Prof. Johnson states that the price of 

 this material is 35 cents per 100 lbs., or 

 $7.00 per ton. Its fertilizing value lies. ex- 

 clusively in the 20 or 30 lbs. of lime, 3J of 

 magnesia, \\ of phosphoric acid, and 1 or 

 2 lbs. of potash in each 100 lbs. But these 

 materials may be procured in other forms, 

 as follows : 35 lbs. of fresh-burned oyster- 

 shell, or stone-lime, will furnish the lime ; 

 15 lbs. of any good superphosphate will sup- 

 ply the phosphoric acid ; the magnesia and 

 potash together may be obtained in 40 lbs. 

 of German potash salts, and there will then 

 be 4 or 5 lbs. of potash and 6 lbs. of sul- 

 phuric acid extra. 



If the lime be slaked with water in 

 which the superphosphate and potash salts 

 have been soaked and partially dissolved, 

 the resulting mass will contain not only all 

 the fertilizing elements of 100 lbs. of leached 

 ashes and more, but these elements will be 

 in such a state of fine division as to render 

 the mixture in all respects equal to the ashes 

 themselves. 



From these data any one can readily 

 calculate the cost in his own locality of a 

 substitute for leached ashes. " It must not 

 be forgotten," adds Prof. Johnson, " that a 

 mixture made of fresh-burned lime should 

 be allowed to become mild by exposure to 

 the air, or its peculiar effects on the soil 

 should be anticipated and provided for." 



Age of Metamorphie Rocks. — " The 



Metamorphism of Rocks " is the title of a 

 paper read at the Association meeting, by 

 Prof. T. Sterry Hunt. The author briefly 

 noticed the changes produced in ro'eks by 



