112 DR. WILSON rOX ON THE DEVELOPMENT OF STRIATED MUSCULAR FIBRE. 



Figs. 29 & 30. Chick from fourth to fifth day. The nucleus now appears prominent on 

 the fibres with some granular matter around it, the whole being enclosed by 

 a membrane. Width of striated portion ^oooo to ^ gooo of an inch ; width 

 of nucleus 4 5^0 of an inch. 



Figs. 31 & 32. Fibres from Chick at fourth and fifth days. Width of whole fibre (fig. 

 31) at a ^^(To of ^^ i^^h ; width of striated portion 22000 to xeooo of an inch , 

 width of whole enlargement at b 25^00 of an inch. 



Figs. 33 & 34. Fibres from sixth to seventh day. Sarcolemma now very apparent. 

 W^idth of striated portion of fibre (fig. 34) X20 00 of an inch. 



Figs. 36 & 37. Fibres from Chick at eighth day. ShoAV great increase of nuclei. 

 Width of fibre (fig. 37) at a oTiVg" of an inch. 



Figs. 38-41. From Sheep half inch in length. Length of fig. 38 ^2^00 of an inch, breadth 

 3-^00 of an inch. Width of fig. 39 at « ssVo of an inch, at h -^000 of an 

 inch, at c ^qoOo of an inch. Length of nucleus in fig. 40 3-3^-0 of an inch, 

 breadth 4^00 of an inch. 



Fig. 41. Shows elongation of a cell (such as fig. 38) with multiplication of its nuclei 

 and commencing striation, and corresponds to figs. 11 & 27 from Tadpole and 

 Chick. 



Figs. 42-44. From Sheep one inch long. Width of whole fibre (fig. 43) at a 4 0^0 of an 

 inch ; of striated portion 8^o"o of an inch. The sarcolemma can be distinctly 

 seen surrounding these preparations. 



Figs. 45 & 46. From human embryo of six weeks. These are magnified only 690 dia- 

 meters, and consequently show less distinctly than those of the Sheep and 

 Chick, the continuity of the sarcolemma outside the nucleus and fibre. 

 Width of fibre (fig. 45) at b 20000 of an inch ; of nucleus y^oo of an inch. 



At fig. 46 is seen a commencing multiplication of the nuclei within the sar- 

 colemma. 



Fig. 47. Stellate cells from heart of Chick between second and third day. Around some 

 a double contour can be seen. X 1850 diameters. 



Fig. 48. Anastomosing fibres from heart of Chick between fourth and fifth days, xl850 

 diameters. 



Fig. 49. Spindle-shaped cells from heart of Chick from fourth to eighth days. 



