DOCTRINE OF SPONTANEANS DISPROVED. 557 
large, and have much small crooked timber divided among them. A 
tree standing in a plantation follows the same law of nature, but by 
judicious thinning and pruning will form a stem of considerable 
length, while in a good growing state, 'care, therefoi'c must be taken 
at all times to have a good head, if you mean to have stem, and when 
you have length of stem the head cannot be too large. Thus the 
fewer trees you have on an acre of land the better, if the tops cover 
all the ground ; for the timber will certainly be of larger dimensions, 
and consequently the more valuable. In plantations grown to limber 
size, a tree that will square a foot is of considerable more value than 
four that square six inches each, as every cai-penter can tell. And 
now we are mentioning timber, let us say a word or two about the 
gi-owing of it. Some great authors tell us that timber cannot be 
good if raised anv wav bv cultivation and maimring, and that every 
method employed must be as near nature as possible to make it 
valuable ; but if the experiments made by practical men may be dc- 
])ended upon, timber that has grown the fastest is the strongest and 
best. It follows, therefore, that land intended for planting, (if not 
very rich) may be trenched and manured according to garden prac- 
tice for a common crop, such as potatoes and turnips. 
I have thus put together the methods I have followed in pruning 
plantations for many years. They will not be of much use to you 
at present, as your plantations are under excellent management ; but 
they are yet voung, and as my experience is of earlier date than 
vours, pei'haps as thev get older, some of my hints maybe of service 
to you, 
I am. Dear Sir, truly yours, 
John Sandys, 
^Ydh, Becemher Zrd. 1829. 
NATURAL HISTORY. 
ARTICLE XII.— DOCTRINE OF SPONTANEANS DISPROVED. 
BY AN IMPORTANT DISCOVERY OF M. CHRENBERG. 
It is well known that by far the greater number of our living natu- 
ralists and physiologists, believe in the doctrine of spontaneant gene- 
ration, chiefly because they could not discover that microscopic ani- 
malcules, or monads as the}' called them, are produced from parents. 
Being, thei'efore, unable to discover this, they forthwith concluded 
