THE FROG — 19 
together. Study carefully one of these glands; note three regions 
distinguished by the different character of the cells. The three 
regions may be called mouth, neck and body respectively. Under 
high power, draw a gland showing clearly the character of the 
cells in the different parts; the drawing should be about 8 or 10 
centimeters in length. 
(b) The submucosa. Examine under high power. The sub- 
mucosa is much thicker than in the small intestine. Along its 
inner margin, adjacent to the mucosa, observe a narrow zone 
called the muscularis mucose, consisting of an inner circular and 
an outer longitudinal layer of non-striated muscle fibers. (In the 
intestine a muscularis mucosa is sometimes found, but never 
well developed. ) 
(c) The muscular layers. Compare with those of the small 
intestine. 
(d) The peritoneum, as in sections of the intestine. 
VII. THE UROGENITAL SYSTEM. 
A. General Anatomy.—Review your observations on the ex- 
cretory and reproductive systems (urogenital system) of both 
sexes, supplementing the study of your own specimen by the 
examination of permanent preparations.. Make an outline sketch 
of the urogenital system of your own frog, including in your 
drawing the large intestine and the cloaca in order to show the 
connection of the ducts and the bladder with the cloaca. If the 
specimen is a female it will be necessary to remove the ovary of 
one side, if this has not already been done, in order to expose | 
the kidneys and ureters; this ovary may be omitted from the 
drawing. On account of their intimate relation to the reproduc- 
tive system, the fat bodies may be included in the drawing. This 
drawing should be about twice natural size. 
How do the eggs produced in the ovary of the female reach the 
exterior? 
B. The Finer Structure of the Kidneys.—In transverse sec- 
tions of a kidney distinguish median and lateral edges, dorsal and 
ventral surfaces. The dorsal surface is usually more convex, the 
lateral edge more acute. 
In a cross-section, find the ureter; this lies on the dorsal side 
