98 



The method of inspecting the eggs in this hatching 

 box is as follows : Two wooden wedges are inserted, 

 one on each side of the uprights attached to the bottom 

 frame to hold them in place. One box is always left 

 empty. The trays in the adjoining box are raised so as 

 to bring the upper one just below the surface of the 

 water and are wedged ; this is examined, and after the 

 dead eggs are removed it is placed in the empty box, 

 lowered under water and wedged. When this is finished 

 another is raised in the box which is being examined, 

 and transferred after inspection to the other box. By 

 wedging them each set of trays is kept in its place, and 

 can be examined systematically. When they are all 

 finished, that box is empty and may be cleaned if nec- 

 essary. Then the trays in the next adjoining box are 

 examined and transferred to it in the same way, and so 

 on with one after the other till they are all completed" 

 and an empty box left at the further end of the row for 

 use on the next occasion. If the water is pure this 

 operation will not have to be performed more than once 

 in two days, as the tendency of these boxes is to clean 

 themselves and to prevent the retention of sediment. 



By the use of the Holton boxes an immense conden- 

 sation ot room can be effected ; each tray will hold more 

 than ten thousand brook trout eggs, and the total num- 

 ber in each box will be about two hundred thousand. 

 Our usual practice with trout eggs is to remove them 

 from the boxes when they are about hatching and place 

 them on the trays or gravel in the troughs where they 

 will have more room, arid can get Out of their shells 

 more readily. • The empty shells will otherwise, some- 

 times clog the wires and stick to the embryos, unless 

 the boxes are examined very frequently during the last 

 stages of development. 



