140 
J. O. SIDDALL. 
The number of these nucleated granules contained in each 
perfect Shepheardella is, of course, very great. They are 
packed so closely that the sarcode seems to owe its density and 
yellow colour to their presence, and yet it is not difficult to be- 
lieve that each one of them may, by the continued exercise of 
the process of free-cell formation, and possibly, also, the exu- 
dation at the same time from each cell of a coating of living 
protoplasm, possess the power of becoming, under favorable 
circumstances, a new individual like the parent Shepheardella. 
The probability of this is increased by the great enlargement 
in size which takes place before the granules are liberated as 
separate living organisms, as shown in PL XV, fig. 13 h. 
The nucleus, which in living specimens appears to be so 
simple, is found by the more deliberate examination of 
mounted specimens to be of exceedingly complex structure. 
It consists of three portions, viz., a lenticular oval body, 
which may be termed the nucleus proper, an embracing but 
not continuous inner coat, and an outer membranous sac 
enclosing the whole. The nucleus proper is an oval biconvex 
cell, bounded by a very delicate wall and filled with proto- 
plasm, which in PI. XVI, fig. 5 h and a will be seen to be 
contracted and coagulated by the action of the reagents round 
the edges of the cell ; and at fig. 4 to be dispersed over its 
whole interior surface. It possesses within it a distinct 
secondary nucleus of somewhat denser protoplasm, and in 
this again a central spot or nucleolus of its own. Of the 
two surrounding envelopes, the inner one is a simple trans- 
parent membrane very slightly roughened or granulated in 
texture, apparently composed of firmly coherent specialised 
protoplasm, and on this the nucleus lies ; the free thickened 
edges of the envelope enfolding but not completely covering 
it (see PI. XVI, figs. 3 4 S, 5 c, 6 c). The outer envelope 
is a simple membranous continuous sac, completely enclosing 
both nucleus proper and inner coat (PI. XVI, figs. 3 c, 5 c?, 
and 6 d). It is perfectly structureless, and so transparent 
that when tightly stretched by the widely opened inner coat 
it cannot readily be distinguished, but is easily seen as a 
somewhat wrinkled thin skin when the inner coat is enfolded. 
Figures 4 and 5 are taken from specimens treated with 
dilute acetic acid and subsequently stained with carmine 
solution. This method of treatment appears to answer better 
than any other for rendering the structure clear, and at the 
same time staining the nucleus proper and its contents, whilst 
the coverings retain pretty much their original colour. 
Picro-carmine, after osmic acid and dilute alcohol, renders 
the nucleus generally very distinct, staining it red, while 
