The Repro ducticn of Diatoms. By J. Newton Coombe. 3 
referred to in William Smith’s Synopsis — I am unable to express any 
opinion upon them ; but that the spore-like bodies shown in my 
photographs may develop into fully formed young diatoms before 
leaving the parent shell, I am satisfied, from the discovery in the 
Port Erin gathering of a frustule of Coseinodiscus containing eight 
pill-box like bodies, some of which presented valve and others girdle 
views similar to those of the parent, and all of which were so far 
silicified as to be capable of fracture upon pressure of the cover-glass. 
Unfortunately the lively movement of the diatom prevented me from 
obtaining more than a blurred photograph of the young frustules ; 
and in refilling the cell after evaporation of the water, I lost the 
specimen, and did not succeed in finding another similar one. 
Photograph No. 6 is that of a portion of a filament of Chsetoceros 
taken from the valve view, in which the contents of one of the 
frustules have divided into two egg-shaped bodies, which under the 
Microscope (but not as focussed when photographed) are seen to be 
again dividing into four bodies. 
Photograph No. 7 is that of a filament of the fresh-water diatom 
Eunotia pectinalis (Kiitz.) in which the contents of the frustules 
are clearly shown to be dividing from two into four portions, and 
there seems no reason to doubt but that this is again similar to what 
takes place in the case of the marine diatoms already mentioned. 
Photograph No. 8 is that of a living filament of the fresh- water 
diatom Melosira varians, in which the contents of several of the 
frustules have divided into spore-like bodies by a process similar to 
that in Chsetoceros and Eunotia. 
Photograph No. 9 is that of the fresh- water diatom, Meridion 
circulare, showing the resolution of the contents into spherical bodies, 
which, it seems fair to infer, although I have not been able to observe 
it as in the case of Eunotia and Melosira, has taken place by a 
process of division similar to that in those diatoms. 
Dealing next with the mode of reproduction described by Mr. 
Murray as a “ rejuvenescence of the cell and the secretion of a new 
frustule within the parent, 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,” I have been fortunate enough to obtain photographs 
from the Port Erin gatherings entirely confirming Mr. Murray’s 
observations in regard to Biddulphia and Coseinodiscus , and estab- 
lishing the occurrence of a similar phenomenon in regard to Ditylum 
and Guinardia. 
Photographs Nos. 10 and 11 are those of three living frustules of 
Biddulphia, the contents of which have been rounded off as described 
by Mr. Murray. 
Photographs Nos. 12 and 13 would appear to be those of further 
•stages in this particular process of reproduction, No. 12 being 
apparently that in which the rounded oft' contents, after undergoing 
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