JOURNAL OF MICROSCOPICAL SCIENCE. 
DESCRIPTION OF PLATE XI, 
Illustratmg Mr. J. Lockhart Clarke’s paper on the Development 
of Striped Muscular Fibre in Man, Mammalia, and Birds. 
Fig. 
1.—Free nuclei and granules from the muscular tissue of the trunk of the domes- 
tic fowl at the end of the fifth day of incubation, magnified 900 diameters : 
a, granules of different sizes; 4, smaller nuclei; c, larger nuclei. 
2.—Larger nucleated cells belonging to the integument, and surrounded by nuclei, 
magnified 420 diameters. 
3.—Free nuclei and nuclear fibres from the same source, magnified 670 diameters. 
4,—Fibres in the first stage of development at the same period, magnified 420 
diameters: a, 6, c, muscular fibres formed by a series of nuclei, cemented 
together by acondensed blastema; d, a single nucleus, with a granular pro- 
cess, and a fine fibre or fibrilla bounding one side; e, a nucleus with one 
granular process ; f, fibres of another kind, apparently belonging to ten- 
dinous or aponeurotic tissue. 
5.—Muscular fibres from the anterior extremity of the chick four hours before the 
end of the sixth day of incubation, magnified 670 diameters: a, 4, nuclei 
cemented together by thin, long, granular processes; c, a series of nuclei 
slightly overlapping each other below, and cemented by a column of con- 
densed blastema. This arrangement is only a repetition of that seen at 4, 
the processes having coalesced to form the column. d. A fibre formed by 
the coalesence of fusiform granular masses, collected round each nucleus. At 
its upper part the fibre has become plain and straight. 
6.—Fibres from the muscular tissue at the end of the sixth day of incubation, 
magnified 420 diameters: a appears to be a tendinous fibre. 
7.—Muscular fibres and nuclear fusiform bodies from the heart of a chick at the 
ninety-second hour of incubation, magnified 420 diameters: 4, fibres 
arranged in abundle; e, c, bodies belonging to tendon. 
8.—Fibrillation of the blastema between the nuclei, with larger fibres in the mus- 
cular tissue, of the chick, on the fifth and sixth days of incubation, magnified 
500 diameters. 
9.—Muscular fibres in process of formation, ten hours before the completion of 
the seventh day of incubation, magnified 420 diameters. At @ several small 
fibres are seen to enclose nuclei and unite at their extremities; at 4, 3, 
other small fibres have formed on a mass of condensed blastema, and be- 
come encrusted with nuclei; ¢ shows a number of communicating fibres, 
with nuclei and condensed blastema between them; d, d, 4, portions of 
similar masses contracted into the form of cells; e, e, two fusiform fibres, 
having the appearance of cells; g, branched fibres, forming an expansion 
of condensed blastema with nuclei. 
10.—a, 6. Fibres developed in the blastema, in contact with nuclei; ¢, striated 
fibre under similar conditions, six days and fourteen hours of incubation, 
magnified 420 diameters. 
11.—Muscular fibres of the chick, in different states of development, at the end of 
the twelfth day of incubation, magnified 420 diameters: d, e, fibres in the 
first stage; 4, two nerve-fibres from a nerve of the leg. 
12.—Same kind of fibres from the chick at the end of the thirteenth day of incu- 
bation, magnified 420 diameters. 
