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When a fragment of a decomposed Boletus is placed under the microscope it will 
be observed that most of the original constituent cells have vanished, the cells 
being apparently more or less replaced by myriads of monads, bacteria and 
vibriones, the special cells of the hymenium, including the basidia and cystidia, 
being amongst the last to disappear. The intercellular juices will be seen to have 
given birth to innumerable fine hair-like crystals, whilst the spores will be observed 
to have suffered no injurious change. Many of the spores will now probably be 
seen in the act of germination amongst the decomposed cells, the crystals, and the 
infusoria. Together with typical spores will be seen many other spores perfectly 
transparent and empty ; these are the exospores which have discharged their 
nuclei. So different do the normal spores and exospores now appear in their 
different aspects that on a superficial examination only they might possibly be 
considered as belonging to two series of spores possessing different functions, or 
even ‘‘ male and female spores,” as recently suggested by Van Tieghem. A large 
number of spores are from the first effete and have no nuclei, others are barren 
because they have escaped the spermatic fluid from the cystidia. 
The observation of the germinating spores is most conveniently made with a 
Boletus which has been kept fora month in very wet air undera darkened bell 
glass. 
According to my interpretation of the meaning of the bodies seen upon the 
hymenial surface of Boletus the reproductive process is exactly the same in Boletus 
with that described by me under Agaricus and Coprinus. In other words the 
hymenium is studded over with three forms of cells. The first are more or less 
globular and barren, the second (named basidia) protrude spicules which carry 
spores (and these spores may be compared with naked ovules), and the third 
(named cystidia) are as I conceive essentially male in their functions. The cystidia 
at length open at their apex and discharge a fluid containing motile granules; 
these granules on bursting act on the spore as the pollen with its tube does on the 
ovule or as the spermatozoid acts on the ovum. After fertilization the spores rest 
for several weeks in the decaying body of the parent ; during this period nearly all 
traces of the spermatozoids are lost, but a considerable change gradually comes 
over such spores as have been rendered fertile. In Boletus the spores are furnished 
with from one to four nuclei; these nuclei after fertilization greatly increase in 
size and translucency ; ultimately they get so large as to greatly distort the outer 
coat of the spore which they at length burst and the nuclei are free. Not unfre- 
quently all the nuclei of one spore become confluent and are discharged as a very 
large solitary nucleus. These discharged nuclei are not true mycelium but the 
first round cells of a new fungus, and the increase goes on by increase of cells, In 
Coprinus the first mycelial threads start from small aggregations of these round 
fertile cells and no doubt the same law holds good in Boletus. Many observations 
prove that new Agarics start from aggregations of round cells upon old mycelium, 
but this does not invalidate the fact that the jirst cells from the spore are not true 
mycelial threads, but the first round fertile cells of anew plant. To trace these 
discharged cells to a perfect Boletus of the second generation would be very diffi- 
cult, and would require continuous observation through an entire year, 
