319 
Extracts from British and Foreign Journals. 
WONDERS OE THE MICROSCOPE. 
By A. S. Copeman, V.S., Utica, N.Y. 
[Continuedfrom p. 276 .) 
It being demonstrated by the microscope that the cell is 
the primordial condition of the animal and the plant, it is es¬ 
sentially necessary that the student of histology should be 
familiar with these primary elements of both divisions of 
the organic world. In the most ordinary form of endogenous 
cell-formation the first phenomenon observed in the parent 
cell is the increase of the nucleus [mesoblast,* Agassiz), which 
becomes elongated, and eventually resolved into two parts. 
These separate from each other, and a partition is formed, 
thus dividing the parent cell into two perfectly distinct spaces, 
each of which incloses a nucleus and half of the contents. 
This mode of cell-formation is continuously repeated as 
long as the growth of the organism continues. The recurrence 
of this endogenous cell-formation is well established in the case 
of the young cartilages of all animals, and in embryonic 
organs in general, in whom from the period at which they 
consist of true cells, the entire growth depends upon the 
multiplication of the existing cells. 
Cell formation by division has also been observed in the 
blood-corpuscles of embryos and the chyle-corpuscles of mam¬ 
mals ; in these the cells first become elongated, and the single 
nucleus divided in two; the cells are then constricted in the 
middle, and finally resolved into two, each with a nucleus. 
To Prof. Kolliker is due the honour of demonstrating by 
the microscope that both voluntary and involuntary muscle 
is resolvable into elongated cells. e ‘l am enabled to show ,” 
says this learned physiologist, (i that in the two-month human 
embryo the earliest forms seen were simple fusiform cells, 
containing in the middle portion one or two elongated nuclei, 
attenuated at each end. In the muscular substance of the 
thigh complete series of forms, from simple elongated primor¬ 
dial embryonic cells, could be traced up to fibres containing 
elongated nuclei, and also presenting the transverse striations, 
so that it could not be doubted that the future muscular 
fibres are derived simply from a growth in length and breadth 
of the original unnucleated fibre-cell.” 
