66 H. JEANETTE ALLEN. 



glycogenated, but they still retain this function to some extent. 



In a seventy-two-hour chick there was an appearance of 

 glycogen in the mesoderm between the two portals and the two 

 sides of the future body-cavity, but as this did not seem consis- 

 tent with other stages, its presence, or the normality of its 

 presence, is rather doubtful. 



In a ninety-six-hour chick a faint trace of glycogen was found 

 in the septum medullae. At four and a half days the glycogen 

 was very distinct here and it remained in this position up to the 

 oldest stage studied, making a very striking mahogany-colored 

 streak along the floor of the medulla (Figs. 12 and 13). From 

 five days on it was found in a similar position along the floor of 

 the spinal cord in its lumbar and sacral regions (Fig. 14). 



At this same age (five days), it appeared in the ectoderm of the 

 anal plate. 



At approximately six days glycogen appeared in some of the 

 muscular tissue around the eyes, forming strings of beads along 

 the fibers of the tissue. This became more and more abundant 

 in later stages (Figs. 15 and 16). 



At an age of from seven to eight days it was observed in other 

 parts of the head region in the muscular tissue below the tongue, 

 and medially in a clearly defined area of developing cartilage 

 which formed a keel-l ; ke structure below the brain and between 

 it and the pharynx. (Fig. 17). 



At this age also glycogen occurs in the muscular tissue along 

 the sides of the body, and at a slightly older stage it appears in a 

 small patch of ectoderm in the nose region. 



At ten days it is found in the cartilage of the head and body 

 quite generally. Fig. 18 shows a trace of it in a developing 

 centrum in the head region. In Fig. 14 it appears in the verte- 

 bral cartilage of the body. Fig. 19 shows it very abundant in 

 the cartilage of one of the developing limbs. Fig. iga shows the 

 same under high power. The glycogen of the cartilage appears 

 as very distinct red spherules which practically fill the cells. 



Glycogen is found in great abundance at this age in the mus- 

 cular tissue, not only in that already mentioned, but also in the 

 more superficial muscles of the head, in the pectoral muscles 

 (Fig. 20), in the muscles of the limbs (Fig. 19), and in fact in 



