No. 2.] ENTERON OF AMERICAN GANOIDS. 41 7 



longer time seems to do no harm. From this the tissue was 

 transferred to 70% alcohol to which a little tincture of iodine 

 had been added. The tissue is washed in this till the alcohol 

 ceases to lose color; then it is transferred to 75% alcohol for 

 a day, after which it is dehydrated and embedded either in 

 paraffin or collodion. 



The cilia of ciliated epithelium are perfectly preserved, so 

 far as can be judged, by each of the above-named hardening 

 agents. 



Various stains were tried, but the most satisfactory combi- 

 nation was haematoxylin and eosin. For separating the mus- 

 cular coats 20/^ nitric acid was used. The tissue was left in 

 the acid until it had sufficiently dissolved the connective sub- 

 stance to permit the ready separation of the fibers. This is 

 effected, usually, in from one-half to two days, depending 

 largely upon the temperature, the acid acting more rapidly in 

 a warm atmosphere. When the tissue has been sufficiently 

 macerated, further action of the acid is prevented by placing 

 the tissue in a saturated aqueous solution of alum, plus 2^0 

 chloral hydrate, in which it may be kept for an indefinite 

 period. This is also a good method for isolating the gastric 

 glands. For isolating the epithelial cells Midler's fluid, picric 

 alcohol, 30-35%, and alcohol, 30-35%, were used; of these 

 Muller's fluid was the most satisfactory. 



It is a source of regret that the material could be examined 

 in a fresh condition only in the cases of Amia and Lepidosteus. 



The outlines of the figures were made by aid of an Abbe 

 camera lucida; the details were put in freehand. 



Common Lake Sturgeon. 



General Form of Enteron. — The conformation of this por- 

 tion of the abdominal viscera is somewhat complex. From 

 the mouth the enteron extends nearly one-half the length of 

 the abdominal cavity, where it doubles upon itself and as- 

 cends several centimeters in front of the opening of the pneu- 

 matic duct. The ascending portion is somewhat to the left 

 of the descending part; the intervening space is filled by a 

 lobe of the liver. At the point above indicated the ascend- 



