ady to undergo development on meeting with
suitable conditions was very manifest, as in those cases in which
preparations were retained under observation for any length of time,
germination rapidly took place in many of the cells; indeed, many
spores already germinating were deposited on the slides. In few
instances did any development take place beyond the formation of
mycelium or masses of toruloid cells, but in one or two distinct
sporules were developed on the filaments arising from some of the
larger septate spores, and in a few others _Penicillium_ and
_Aspergillus_ produced their characteristic heads of fructification.

With regard to the precise nature of the spores and other cells
present in various instances little can be said, as, unless their
development were to be carefully followed out through all its stages,
it is impossible to refer them to their correct species or even
genera. The greater number of them are apparently referable to the old
orders of fungi--_Sphaeronemei_, _Melanconei_, _Torulacei_, _Dematiei_,
and _Mucedines_, while some probably belonged to the _Pucciniei_ and
_Coaemacei_. Amongst those belonging to the _Torulacei_, the most
interesting was a representative of the rare genus _Tetraploa_.
Distinct green algoid cells occurred in some specimens. Then follow in
the report details of observations made on the rise and fall of
diseases, of which diarrhoea, dysentery, cholera, ague, and dengue
were selected and compared with the increase or diminution of
atmospheric cells. The conclusions arrived at are:--

"Spores and other vegetable cells are constantly present in
atmospheric dust, and usually occur in considerable numbers; the
majority of them are living, and capable of growth and development.
The amount of them present in the air appears to be independent of
conditions of velocity and direction of the wind, and their number is
not diminished by moisture.

"No connection can be traced between the numbers of bacteria, spores,
&c., present in the air, and the occurrence of diarrhoea, dysentery,
cholera, ague, or dengue, nor between the presence or abundance of any
special form or forms of cells, and the prevalence of any of these
diseases.

"The amount of inorganic and amorphous particles and other debris
suspended in the atmosphere is directly dependent on conditions of
moisture and velocity of wind."

This report is accompanied by fourteen large and well-executed plates,
each containi