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centrifugal order, thus producing a six-celled spore. The mature 
spore is slightly constricted at the septa. 
The spores are produced in short chains in acropetal order. When 
the basal spore is nearly mature, a minute papilla appears at its apex ; 
this papilla gradually increases in size and forms a second spore, 
which in turn gives origin at its apex to a third spore. I have never 
seen more than three spores in a chain. 
When the basal spore of the chain is mature it falls away from 
the sporophore, carrying the immature spores along with it; the 
latter consequently attain their full size, often from a very small 
beginning, after becoming free from the sporophore and from each 
other. This explains the presence of spores of various sizes and with 
a varying number of septa, seen on examining microscopically species 
of Heterosporium, Helminthosporium , and Cladosporium. The 
gradual growth of young isolated spores can be readily followed in a 
nutritive medium. 
The minute projections on the epispore gradually increase in size 
until the spore is mature. Prominences on the epispore are produced 
by two distinct methods ; in the present example, if a nearly mature 
spore is plasmolysed after its contents have been stained, it will be 
seen that the protoplasm is attached to the inside of the epispore by 
very fine strands at those points corresponding to the minute pro- 
jections on the outer surface. A similar condition of things may be 
observed in many other acrogenously formed spores. These warts or 
spines, as the case may be, must be looked upon as due to localized 
points of growth, caused by the continued contact of the epiplasm 
with the cell-wall, and not as being due to the apposition of matter, 
as considered by some observers. 
The second type of epispore ornamentation is met in the asco- 
spores of various species of subterranean fungi belonging to the 
genera Tuber ) Sphserosoma , Hydnobolites, &c., the zygospores of 
Syzygites, and the oospores of species of Cystopus, Plasmopora, and 
Peronospora. The wall is in all cases thick, at first smooth but 
eventually, owing to local contraction, it becomes irregularly rugulose, 
nodulose, or furnished with prominent ridges or plates, which in some 
species anastomose to form a more or less regular network resembling 
a honeycomb. The markings on the spores of all Myxogastres are 
due to this method of local contraction of the external surface of the 
spore. 
If spores of the present type are treated for some time with dilute 
potassic hydrate the contracted portions swell, and the wall becomes 
smooth and even, whereas this is never the case with those spores 
where the projections are due to local growth of the epispore. 
At the moment of maturity, the spores germinate within twelve 
hours, when placed in a suitable medium. Each cell of the spore is 
capable of giving origin to a germ-tube, but this rarely occurs ; as a 
