420 THE AMERICAN MONTHLY [Dec. 



with the intestine; trace it forwards and find its anterior 

 end (in the body wall above the terminntiou is located a ' 

 small ovary). The general anatomy of the organs is the 

 same in the male smelt. Cut out a small portion of an 

 oviduct and tease it ([)ull it to bits) in water, as you do 

 so you will be able to recognize that it contains great 

 numbers of small spherical yellow objects, ova. Crush 

 one on a slide and examine it with the high power, you 

 can now recognize the ceil wall or vitelline membrane 

 which invests the ovum and the grains of yolk (there is 

 in addition a central nucleated mass of protoi»lasm which 

 should be carefully studied in a prepared slide if possible). 

 The contents of the spermiduct should be studied in the 

 same way, the spermatids are visible under the higher 

 power (if preserved) as elongata filamentous objects; the 

 size of one of those is infinitesimal in comparison with 

 the size of one of the ova. The kidneys are situated in 

 the dorsal wall of the body cavity, close to the vertebral 

 column, they are covered by the peritoneum and do not 

 lie in the body cavity. They can be recognized by their 

 dark red color (a duct ureter leads from tnera to join the 

 gonadial duct as it passes to the cloaca). 



12. The Muscular System. — Boil a fish thoroughly, 

 then remove the skin so as to study the muscles, note 

 first that throughout the trunk and post-abdomen, the 

 muscle masses are segmented, i. e,, they are made of 

 similar portions that are repeated the length of the body; 

 called myotomes; the number of the myotomes is the same 

 as that of the vertebrate; each myotome is composed of 

 parallel ^6res whi<di run from one rib, or posteriorly from 

 the level of one vertebra, to the next. Draw figures 

 showing the myotomes in situ, and of one myotome sep- 

 arated from the rest. Mount a few of the muscle fibres 

 in water for microscopic examination, tease them into the 

 finest possible masses, isolating single fibres if possible, 



