1896 - 97 .] Mr George Murray on Marine Diatoms. 213 
the fine spines of the parent), and the stages of contraction, &c., 
of the cell-contents to be precedent to its development. 
These agree well enough with the u condensed endochrome ” of 
Lauder, quoted above in speaking of Baderiastrum and Chcetoceros . 
These bodies interested me much at the time, ignorant as I then 
was of any observations of the occurrence of endocysts in diatoms, 
and I took the process (as indeed it is) to be a form of rejuvenes- 
cence of the diatom cell. I have fortunately been able to throw 
some light on their subsequent history. In August I found the 
same bodies extremely plentiful on the west coast, outside the 
Clyde sea area, from the Sound of Islay to Loch Hourn. They 
were mostly a good deal longer (fig. 4) and frequently in a state of 
division (fig. 5). They exactly resembled in every botanical 
character the young “ cysts ” of spring, and there was at the same 
time an almost entire absence of the characteristic form of 
Biddulphia mobiliensis. It appears, then, that these reproductive 
bodies possess the power of dividing and multiplying to a great 
extent before they assume the characteristic parent form of B. 
mobiliensis. From their abundance I should not be surprised to 
hear that they have been described under a separate specific name. 
[Note . — During the first week of December the characteristic 
form of Biddulphia mobiliensis was abundant on the west coast, 
and the young forms observed in August were not to be found. 
Presumably they had developed in the meantime into the mature 
forms. — 10th December 1896.] 
On the same plate (fig. 7) there is represented a specimen of 
Coscinodiscus concinnus with another inside it. At first I took 
this (and others of the kind) to be merely accidental intrusions — 
the more readily that I had observed a large number of such 
intrusions in a rich haul of Coscinodiscus near the Bell Bock. 
After turning the specimen over and over many times, I was, 
however, forced to the conclusion that there was here a young 
Coscinodiscus veritably within another. I subsequently met with 
many such, especially in Loch Fyne in spring, and I naturally put 
it down, as in Biddulphia , to a rejuvenescence of the cell. Among 
many such examples I found the form figured on Plate II. figs. 1, a 
and 1, b. It puzzled me greatly to account for it. We have here 
within the parent form two young diatoms at first sight singularly 
