The Reproduction of Diatoms. By J. Neirton Coombe . 5 
found what appears to be pretty clear evidence that Biddulphia is 
reproduced by the division of the contents of its cells into spore-like 
bodies, as well as by the secretion within its valves of new frustules ; 
and also that Chastoceros must be added to those marine diatoms 
which reproduce themselves by rejuvenescence of the cell and the 
secretion of a new frustule within the parent. 
Photograph No. 21, taken at a magnification of 180 diameters, is 
that of a frustule of Biddulphia, in which may be clearly seen the 
outlines of the valve view of two young Biddulpliias, the contents of 
each of which have become divided into numerous spore-like bodies 
similar to those in Coscinodiscus (photo. No. 5). 
Photograph No. 22 is also that of a frustule of Biddulphia, con- 
taining two young Biddulphias. This photograph is chiefly inter- 
esting on account of the young individuals being so far developed 
within the parent valves as to bear both girdle and spines, and there- 
fore presumably to be incapable of growth ; whereas in the cases 
already shown (photos. 10, 11, 12, and 13) there was an intermediate 
stage, during which the contracted contents of the parent frustule, 
having secreted a non-siliceous membrane or sac of the same shape as 
the parent, but without any trace of spines, underwent self-division, 
and were apparently capable of growth after leaving the old valves, 
but before silicification took place (photo. No. 12). 
