MISCELLANY. 



251 



member, account for the inequalities in 

 the moon's motion, but it rested on no 

 independent basis. Since that time, Prof. 

 Newcoinb has devised a method of testing 

 this question by totally different means, 

 viz., by an examination of the eclipses of 

 Jupiter's first satellite ; and this test has 

 been applied by Mr. Glasenapp, an astrono- 

 mer of Pulkova. Mr. Glasenapp's researches 

 indicate with great certainty that the earth's 

 rotation is not strictly uniform, and that 

 Prof. Newcomb's hypothesis is sustained. 

 The accurate determination of the amount 

 by which the earth is fast or slow is yet to 

 be reached, but we must accept two im- 

 portant facts as probable : 1. That the 

 earth's rotation time is not strictly con- 

 stant. 2. That the inequalities in the 

 moon's motion are largely, if not wholly, 

 due to this. 



Growth and Reproduction of the Ant- 

 lers of the Deer. John Dean Caton, whose 

 observations on the natural history of the 

 American Cervidte are familiar to the read- 

 ers of Mr. Darwin's writings, contributes to 

 the American Naturalist for June an im- 

 portant paper on the " Structure and Cast- 

 ing of the Antlers of Deer." He shows, in 

 the first place, the substantial identity of 

 structure between the antlers and the ordi- 

 nary bones ; in fact, the antlers are external 

 bones, of very rapid growth, which mature 

 speedily, die, and are soon thrown off; while 

 all other bones are very slow of growth, and 

 persist through life. 



The process of growth is as follows : The 

 old antler having fallen off, the blood-ves- 

 sels of the periosteum at its butt are rup- 

 tured, producing a copious flow of blood. 

 Next, the periosteum grows over the cavity 

 in the top of the pedicel, or process of the 

 skull on which the antler stood. On the 

 approach of spring, this covering becomes 

 inflamed, resembling a blood-blister. It 

 rises up rapidly, new systems of blood-ves- 

 sels forming in it, till its height is twice its 

 diameter ; then an osseous deposit is com- 

 menced at the circumference of the top of 

 the pedicel. As this deposit rises it thick- 

 ens very slowly, the upper extremity pre- 

 senting a thin, serrated edge. Blood-vessels 

 from the periosteum traverse this tissue, 

 supplying it with nourishment. This is the 



source of supply from without ; but there 

 are internal sources also, viz., arteries pass- 

 ing up through the pedicel, and answering 

 to the medullary arteries of long bones. 



At the extremities, first, the deposit of 

 earthy salts goes on till this fills up the 

 canals leading from the periosteum into the 

 bony mass, so that the circulation through 

 them is obstructed ; and this process goes 

 on till all communication between the in- 

 ternal and the external blood-vessels is sev- 

 ered. The animal is now prompted, by 

 some natural impulse, to rub off this outer 

 covering, while it is gorged with blood. 

 The cavities in the branches and the upper 

 portion of the beam soon become hardened 

 throughout, and the solid wall in the lower 

 part much thickened. Before the central 

 section has become solid, the nutrient ves- 

 sels are obstructed below, and the deposit 

 of bony particles arrested, while yet the 

 larger portions of the antler are more or 

 less porous. This makes the antler lighter, 

 without seriously diminishing its strength, 

 for its walls are braced within, in every im- 

 aginable direction, by thin plates of bone. 



In the mean time, the lower extremity, 

 too, becomes more and more compact, and 

 the pedicel, which, during the active growth 

 of the antler, was open and porous, com- 

 mences a new deposit of laminae in its cavi- 

 ties. But now, all sources of nutriment 

 having been cut off, the antler dies, and is 

 removed by a singular process. One of 

 the systems of blo^od-vessels which supply 

 nutriment to the growing antler commences 

 active operations to undermine it. The ab- 

 sorbents of these blood-vessels attack the 

 point of junction between the antler and 

 the pedicel. They do not carry away the 

 surface of the bone evenly, so as to make 

 it smooth, but, as it were, they remove al- 

 ternate particles, till the union, which be- 

 fore was so firm that no force could break 

 it at the point of juncture, has become so 

 weakened that the antler is detached by 

 some slight violence. 



A Remarkable South American Valley. 



According to Iron, the upper valley of the 

 Bio Madeira, one of the chief tributaries of 

 the Amazons, rivals California and Austra- 

 lia in mineral wealth. This valley, which 

 contains about 400,000 square miles, is mar- 



