AGRICULTURAL ZOOLOGY. 349 



where the dorsal fin should be, and continuing uninterruptedly around the caudal, and ter- 

 minating with the anal fin, or rather where it should 'K>. 



This finlike substance undei-goes a constant change as the fish grows older. At fourteen 

 days, the dorsal, adipose, caudal, and anal fins are plainly seen ; but as yet none of them 

 have rays, except the caudal, in which they are very distinct. The rays of the caudal fin 

 are first apparent at the centre, although the general form of the rudimentary tail is very 

 unsymmetrical, the superior lobe being the larger, and the outline not unlike that of the tails 

 of many heterocercal fishes. At this age the fish has more than doubled its former length ; 

 the mouth, gills, and abdominal viscera are visible : and it manifests a desire to take food by 

 nibbling at the unhatched eggs, and pieces of meat placed in the vessel containing; them. Its 

 color is now materially changed, being of darkish gray on its back and upper portions of its 

 side. The sack suspended from the abdomen at this time becomes smaller and less globular 

 in form, being more contracted anteriorly and posteriorly. The habits of the little creature 

 are also much changed, as it now swims smartly, and endeavors to hide itself whenever 

 disturbed. 



Owing to imperfections in our arrangements where we placed the eggs for hatching, accu- 

 mulations of sediment buried them up, destroying them by hundreds ; this accumulation was 

 much more fatal when the embryo fish was nearly ready to make its exit from the egg. To 

 avoid their further destruction, on the 26th of January we brought the remaining e.u 

 our office, and placed them in a glass jar, and supplied them and the young fish with fresh 

 water daily. In this situation they have remained until the present time, the young fish 

 making their appearance from day to day, the last one rupturing its oval envelope on the 

 10th day of February. I have seen as many as six make their appearance in as many 

 minutes. The temperature of the water at the spring was 42 Fahrenheit. Since they were 

 brought to the office, the water in which they have been kept has varied from 42 to 50. 



This experiment has afforded us one of the finest opportunities to be de>ired for the study 

 of embryology ; but professional duties have prevented u^ from making as minute observations 

 as we could have wished. We have, however, repeatedly and distinctly seen the blood-cor- 

 puscles in the returning veins enter the auricle of the heart and then pass into the ventricles, 

 and from tlieuee into the aorta. Altogether, it lias afforded us one of the most j.le.-isiim; and 

 instructive lessons in the early stages of animal existence that we have ever had. Another 

 fact, in which all are interested, has been clearly demonstrated : Every one who may be so 

 fortunate as to possess a spring of water of moderate size can rear this charming fish in 

 great numbers, and the streams that have been depopulated by the untiring zeal of the 

 angler can be replenished with a little trouble and at a small expense. 



After the eggs have been obtained from the female fish and impregnated, it is necessary to 

 remove them to a suitable place for incubation. Messrs. Ackley and Garlick adopted the 

 following plan: At the head of a spring we built a house eight feet in width by twelve feet 

 in length. We placed a tank made of two-inch plank four feet wide by eight feet long, 

 and two feet deep, in the end of the building nearest the bank. The water from the spring 

 enters the tank through a hole near the top, and escapes through a similar hole at the other 

 end, from whence it is received into a series of ten successive boxes. These boxes are 

 eighteen inches long, eight inches wide, and six inches deep, and are so arranged that the 

 first box is much higher in the series than the last one. They must be filled with clean sand 

 and gravel to the depth of about two inches, the sand being placed at the bottom. The im- 

 pregnated eggs are to be scattered over and among the gravel, care being taken not to have 

 them in piles or masses. The boxes should be carefully examined every few days, after the 

 eggs have been deposited in them, and all the eggs which have lost their vitality should at 

 once be removed. This may be effected with a pair of forceps made of wire, the jaws of 

 which should be flattened a little, in order to seize the egg with greater facility. The eggs 

 which have lost their vitality may very readily be distinguished from the others by their 

 whiteness. 



It is very desirable that pure, clear water should be used, in order to avoid a deposition 

 of sediment, which is very destructive to the eggs, particularly towards the close of the term 

 of incubation. When sediment is found to be accumulating, the water should be agitated 



