JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
June 29, 1882. ] 
529 
When a man builds a house it is of no advantage to 
him to know how to make his own bricks, for he can 
purchase them better and more cheaply; so it is with 
the vast majority of cultivators of Mushrooms, and 
beginners especially will find it far more economical 
to purchase good Mushroom spawn than to endeavour 
to make it, and fail. After a person has become com¬ 
petent as a Mushroom grower and contemplates culti¬ 
vating the esculent on a large scale he will have gained 
experience that may enable him to make his own 
bricks of spawn, with little instruction from others, or 
in other words he will be able to turn the information 
he gains to profitable account. This is the course 
that Mr. Barter pursued. He first grew Mushrooms 
and then commenced “spawn-making” on a small 
scale; and proving equally successful in both the 
demand for bricks increased, and can only now be 
met by a supply of thousands of bushels annually. 
The bricks, it may be stated, are 9 inches long, G wide 
and 2 deep, there being sixteen of these to the bushel. 
There are other extensive manufacturers of Mushroom 
spawn, and the supply for home and export purposes 
amounts to many tons annually. It is to the advantage 
of purchasers of Mushroom spawn that the railway 
charges for it are low, as it is transmitted under the 
lowest scale but one—namely, manure ; indeed, the 
bricks mainly consist of manure in a dried state, which 
is simply the medium for preserving and conveying the 
mycelium that produces the Mushrooms. These bricks 
are composed of soil and manure. When partially dried 
and in the right condition small portions of “ spawn ” 
are inserted, and on being subjected to a genial heat the 
mycelium penetrates the entire mass. The bricks are 
then packed in open sheds in a manner that permits 
the air to circulate amongst them, and when kept cool 
and dry the mycelium retains its strength and vitality 
for years. Some idea may be formed of the extent of 
the trade in “ Mushroom bricks,” and of the manner 
in which they are stored, on reference to the annexed 
engraving of a portion of a shed in a Mushroom spawn 
manufactory (fig. 106). 
THE PREPOTENCY OF VIRGIN MUSHROOM SPAWN. 
A singular circumstance remains to be noticed— 
namely, the prepotency of “ virgin spawn,” or the 
mycelium directly produced by the spores. It is well 
known that the mycelium can be transmitted from 
brick to brick, and may be so increased time after time, 
and year after year, but it is by no means well under¬ 
stood that it is more or less weakened by every such 
transmission. This probably will be “ news to a 
great number of readers, and in all probability it will 
afford the solution to some of a difficult problem. 
There are not many gardeners who have been long 
engaged in Mushroom culture who have not been per¬ 
plexed now and then by the comparative failure of a 
bed. The materials and management were the same 
as before, and the bricks employed appeared good and 
were beyond doubt permeated by the mycelium, yet 
the crops resulting were unsatisfactory, the produce 
either being small or the beds soon exhausted, or both. 
It probably never occurred to the cultivators to inquire 
how far the mycelium had been weakened by inherent 
exhaustion consequent on a course of unintermittent 
propagation. This is a very interesting and important 
question. It is found in practice that to insure 
“ strong ” mycelium capable of producing the heaviest 
crops of the finest Mushrooms we must go to the 
original source and procure it as nearly as possible 
direct from the spores. Nor is it surprising that this 
should be so ; indeed it would be more surprising were 
it otherwise. Given equal conditions for culture, seed¬ 
ling plants of all kinds are stronger than those raised 
from portions of pre-existing plants; and further, it 
will not be disputed that excessive forcing and propa¬ 
gation may result in the degeneration of a species or 
variety of phanerogamic plants. Indeed if it were not 
so the old axiom would not have been established that a 
“ strong plant cannot be made from a weak cutting.” 
The same principle applies with at least equal force to 
the cryptogams; and therefore reasoning by induc¬ 
tion alone we have no right to expect strong Mush¬ 
rooms from weak mycelium. But induction and 
Fig. 106. 
physiology aside, we have the evidence of facts in 
support of the proposition in question, and experience 
teaches that this aspect of Mushroom culture cannot 
with impunity be ignored. Mr. Barter is careful never 
to use spawn or mycelium of more than two genera¬ 
tions from the spores—that is to say, he finds it to his 
advantage to give a guinea for a small portion of virgin 
spawn not equal in bulk to half a crown’s worth of the 
manufactured article for the purpose of impregnating a 
few bricks. It is from these bricks—the first remove— 
that the stock is raised that he himself uses and sells, 
bricks made for those who insist on a “ cheap ” article 
being permeated with mycelium a generation or more 
older, and consequently weaker. It will produce Mush¬ 
rooms, and under favourable conditions good crops, but 
not such profitable beds and splendid produce as he never 
fails to obtain, and which he knows by experience it is 
impossible to obtain from weak second-class spawn 
that never ought to be distributed. Every gardener 
