456 SIMON H. GAGE 
becomes most condensed at the animal pole and finally in 
the medullary region which gives rise to the central nervous sys- 
tem. In embryos 5 to 10 mm. long it is marked in the central 
nervous system. It is at this time present between the gran- 
ules of food yolk, also in the myotomes, notochord, connective 
tissue, nephric system, cardiac muscle, liver diverticulum, and 
epidermis. 
In embryos of 10 to 17 mm., in which the food yolk has 
mostly disappeared, glycogen is present as in the younger em- 
bryos, and has appeared in the brain plexus, retina, and auditory 
epithelium. It is also present in the enteric epithelium. 
With larger, well fed specimens, besides the nervous system, 
the tissues containing glycogen are those of the heart, both 
auricle and ventricle, branchial epithelium, thyroid duct, bran- 
chial cartilages, and their striated muscles, and the muscle of 
the velum, which has only a striated periphery. The glycogen 
is in the granular non-striated central part of the velar muscle. 
In the digestive tract it is found in the gall duct and in the 
liver; also in the intestinal epithelium, especially the terminal 
third. In the urinary system it is found in the nephrostomes, 
and in both pro- and mesonephros, also in the Wolffian duct. 
It is present in skeletal muscles, the notochord, the primitive 
skull cartilages, the ear- capsule, the fat cells, around the central 
nervous system and that on the ventral side of the notochord, 
some of the epidermis, expecially that of the branchial region 
and the oral hood, the epithelium of the nose and the ear. 
AMBLYSTOMA PUNCTATUM 
* 
In this salamander, as with most of the Amphibia, the inde- 
pendent life of the young commences very early, and on the alert- 
ness in escaping enemies and in obtaining food depends its exist- 
ence. Going with this early activity is the presence of glycogen 
in large amount in the unsegmented egg, and in all stages of 
segmentation. During segmentation glycogen is more abun- 
dant in the animal than in the vegetative pole of the ovum. 
While glycogen is more abundant in the animal pole, as segmen- 
