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accumulated in the wall of the larger, completed fat-cells, 
and a small number of fatty molecules are seen free, perhaps 
in consequence of the mode of preparation; but most is seen 
in what are believed to be fixed connective-tissue-cells. 
Migratory cells are seen in great abundance, but are not 
different from the white corpuscles of the blood, and do 
not contain fat. The genuine young fat-cells have no 
membrane, and look at first sight like a heap of fatty mole- 
cules varying in size; they are angular or spindle-shaped or 
polygonal, and only occasionally, when they contain several 
larger drops of fat, are they round. The smallest of them 
hardly exceed in size the normal fixed connective-tissue-cor- 
puscles. Although it might seem natural to suppose that 
the migratory cells should be the early stages of fat-cells, no 
evidence of this could be found. The fat-containing cells 
never show spontaneous movements; pigments introduced 
into the blood pass into the migratory cells, but never into 
the fat-containing cells. 
Observations were also made on fishes, which in the spring, 
when their nutrition is active, give excellent objects. A 
small portion of the parietal peritoneum is carefully stripped 
off and laid on a glass in iodized serum; if surrounded by a 
ring of oil and covered with thin glass it preserves its appear- 
ance, and even the mobility of its cells for as long as half a 
day. Migratory cells are seen in great abundance, and also 
young fat-cells, but these structures seem to be perfectly dis- 
tinct from one another ; the migratory cells never containing 
fat, and the fat-containing cells having the closest resemblance 
to the fixed connective-tissue-cells. Besides these forms, 
however, there are others, which have previously been noticed 
by Leydig as “ mulberry-shaped fat-cells,”’ which appear to 
be nothing else than ready-formed fat-cells, which increase in 
size by the accumulation of fatty granules in their periphery. 
These forms are met with rather on the outside of a fatty 
lobule. Neither in the mesentery nor in the medullary 
tissue of bone could Flemming find any evidence that the 
production of fat begins, as has been supposed, in any special 
round cells, but always in ready-formed connective-tissue- 
cells. In embryoes (of the rat, &c.), the fat production 
seemed to take place in cells of all kinds, among which were 
round embryonic cells. 
In his observations on the wasting or absorption of fat, 
Flemming comes to the conclusion that the fat-cells become 
ultimately converted, not into a “ serous fat-cell,” as has 
been said, but simply into the ordinary flattened connective- 
tissue-cell ; in fact, that the process is precisely the converse 
