500 Recent Literature. [June, 



surely taken that the reader at the end is convinced that the 

 results derived from so many facts must be well founded. 



In 1837, in a short paper on the " Formation of Mould," the 

 author showed " that small fragments of burnt marl, cinders, 

 &c, which had been thickly strewed over the surface of several 

 ' meadows, were found, after a few years, lying at the depth of 

 some inches beneath the turf, but still forming a layer." This 

 was due " to the large quantities of fine earth continually brought 

 up to the surface by worms in the form of castings." This sub- 

 ject has been faithfully followed up through a period of over forty 

 years. 



After describing the structure and habits of the earth-worm, 

 Darwin shows that they burrow both by pushing away the earth 

 on all sides, the pharyryc being, as .Perrier had shown, pushed 

 forwards into the end of the head, causing it to swell out, and 

 thus push the earth away on all sides, while also the worm swal- 

 lows the dirt, which passes through the body. In this way worms 

 may penetrate to a depth of from three to eight feet. By their 

 great numbers and continued activity earth-worms bury small, and 

 often great stones left on the surface. In many-parts of England 

 it is estimated that a weight of more than ten tons of dry earth 

 annually passes through their bodies and is brought to the sur- 

 face on each acre of land ; so that the whole superficial bed of 

 vegetable mold passes through their bodies in the course of every 

 few years. Moreover they triturate and thus disintegrate parti- 

 cles of rock, and thus aid in the denudation of land. By their 

 action ancient earthworks and tumuli are lowered, and old ruins, 

 pavements and stone walls are either buried or perceptibly low- 

 ered, and thus the humble earth-worm acts in the end as a not 

 unimportant geological agent. 



The Microscope in Medicine, by Lionel S. Beale, MB, 

 F.R.S. 1 — This is the fourth edition of a well-known and valuable 

 work, by one of the most practiced microscopists of the United 

 Kingdom. 



The introduction consists of an able plea for encouragement 

 and assistance in the scientific investigation of disease, and is fol- 

 lowed by nearly 200 pages devoted to a description of the apparatus 

 necessary for the examination of objects of clinical importance,- 

 the practical operations required for their demonstration, and the 

 methods of recording the appearances observed. 



In this portion of the work full directions are given for harden- 

 ing, boiling, freezing, rendering transparent or opaque, preserving, 

 mounting, coloring, cutting sections, injecting, and other pro- 

 cesses necessary for ' 



1 College of Ph 



I'-.-i.' 



