2 
Transactions of the Society. 
Port Erin Station of the Liverpool Marine Biological Committee 
with tubes containing the results of weekly tow-nettings made by the 
Curator during the early months of the present year, under condi- 
tions as far as possible similar to those recorded by Mr. Murray. At 
the same time I set to work to further examine and photograph the 
contents of several species of fresh-water diatoms, as to which I have 
for some years observed indications of their resolution into spore-like 
bodies similar to those noted by Mr. Murray in the case of the marine 
species. Although in the first instance the contents of the Port 
Erin tubes were fixed in accordance with Mr. Murray’s formula, I 
soon found out that, for purposes of accurate observation and photo- 
graphy, it was essential that the diatoms should be examined while 
living as well as after death. Thanks to the exceeding pains taken 
by the Curator (Mr. H. C. Chadwick), and notwithstanding re- 
peated failures, I was able to examine and photograph a sufficient 
number of living specimens in a fresh and healthy condition, to 
permit of the illustration of the. observations of marine diatom 
reproduction recorded in the present paper. 
Mr. Murray’s discoveries led him to the conclusion that certain 
marine diatoms “ may reproduce themselves, either by a rejuvenes- 
cence of the cell and the secretion of a new frustule within the 
parent (. Biddulphia , Coscinodiscus, and possibly Ditylum) which, 
escaping on the separation of the parent valves at the girdle, may 
grow, divide, and multiply before fully attaining the characteristic 
external sculpturing and adornment of the parent (. Biddulphia ) ; or 
the number of the offspring may be increased by preliminary division 
of the protoplasm into two, four, eight, and sixteen ( Coscinodiscus ).” 
Dealing first with the last named mode of reproduction, I have 
prepared ten photographs, the first six taken from the Port Erin 
gatherings made in February and March of the present year (1898), 
and the remaining four from fresh-water gatherings made in the 
neighbourhood of Sheffield about the same time. 
Photograph No. 1 shows the contents of a Coscinodiscus dividing 
into two portions, such division being evidently not the ordinary 
process of diatom division, which would be invisible from the valve 
view at which the photograph is taken. 
Photographs Nos. 2, 3, 4, and 5 are those of other frustules of 
the same species, taken from the same gathering as No. 1, in which 
the contents are dividing, or have divided, into four, eight, sixteen, and 
thirty-two spore-like bodies. 
Mr. Murray infers from his interesting discovery in Loch Fyne 
of what he describes as “ packets ” of four, eight, or sixteen young 
Coscinodisci “ held together in all cases by a fine membrane,” that 
this division of the contents of the frustules is preliminary to the 
formation of these “ packets.” 
Not having met with any such “ packets” — which I- take to be 
altogether different from the cysts containing “ broods of diatoms ” 
