OF STEIATED MUSCULAE FIBRE. Ill 



Figs. 2-5 are further stages of the elongation of fig. 1 ; fig. 5 measured -^jq of an inch 

 in length, t^-q of an inch in breadth. Their nuclei averaged tooo of an inch 

 in length, -g^you to 5-^00 of an inch in breadth. In fig. 4 a faint appearance 

 of striation is becoming visible, which is much more apparent in fig. 5, where 

 it can be seen that the striation passes by insensible gradations into the con- 

 tents of the rest of the cell. 



Fig. 6-10 are cells with many nuclei. In figs. 8, 9, & 10 striation is already appearing. 



Figs. 11-13 are cells whose pigment has partially disappeared, and around which a mem- 

 brane is distinct. The membrane is best seen on the striated side of fig. 11 

 (seen in profile). The contents of the cells are seen to be difierentiated into a 

 granular portion and a striated. The nuclei are found in the former. Length 

 of fig. 13, 4X0 of an inch, breadth xwo of an inch ; breadth of central band, 

 5 0^0 of an inch ; length of nuclei, -jwo of an inch ; breadth of nuclei, ^qqq 

 of an inch. 



Figs. 14-16 show portions of fibres in more advanced stages of same process. Total 

 breadth of fig. 16, 2"<^oT) of an inch; breadth of striated portion, -foroo of an 

 inch. The membrane with granular contents within it can be traced over the 

 whole of this latter fibre. 



Fig. 17 is a further stage of figs. 8-10, where the nuclei lie transversely to the fibre. 



Figs. 18 & 19 are front and profile views of fibres produced by the elongation of cells 

 like fig. 5; fig. 19 is seen surrounded by a distinct doiible outline. Width 

 of whole, inckiding membrane on each side, g-inro of an inch ; width of 

 striated portion, egVe of an inch. Such fibres may narrow at their extremi- 

 ties to a width of i^o oo of an inch. 



Fig. 20. Instance where a divided fibre was found in the tail of the Tadpole; the mem- 

 brane (sarcolemma) was seen continued on each division. 



Fig. 21. Fibre from the tail of a Tadpole one week old; striated portion has greatly 

 increased in proportion to rest of contents of sarcolemma; nuclei are seen 

 within sarcolemma, but external to striated portion. Width of whole, xiVo 

 of an inch, of striated portion, t^to of an inch. 



PLATE VI. 



Figs. 22-38 represent the development of muscular fibre in the Chick X 1850 diameter. 

 Figs. 22-26 stages found after forty-eight hours of incubation. 



Fig. 22. Measures xrVo of an inch in length x 5-5V5 ^^ breadth. Diameter of nucleus 

 Wiro X 7 0^0 of an inch. Length of fig. 24 ttoo of an inch ; breadth 3^0 

 of an inch. 



Figs. 27 & 28. From Chick after seventy- two hours' incubation. Length of fig. 28 j\q 

 of an inch ; breadth at a 50^00 of an inch, at b xwo of an inch. 



