REPORT OF COMMISSIONERS OF INLAND FISHERIES. 121 



the older individuals reach the fourth stage, for the fourth-stage 

 lobsters are endowed with strength, sagacity, directive power of move- 

 ment, and voracity of appetite far beyond that of the other stages. 

 When, through a difference in age, a numljer of lobsters enter the 

 fourth stage considerably in advance of the others they become veri- 

 table "sharks," as they are jocularly called by the attendants. On 

 this account, in the first experiments with wooden cars a considerable 

 loss was sustained because certain boxes were reserved as hatching 

 boxes and the fry rather than the "hens" were periodically removed 

 (fig. 5) . It being impossible to get them all out at one time, those that, 

 remained were often taken out together with a younger lot and later 

 on, became "sharks" to this brood. 



Circulation current. — For the benefit of the fry there is no doubt an 

 optimum current within the car. The current can be controlled to a 

 surprising degree by manipulating the propellers, although the num- 

 ber of revolutions per minute remains constant. A slight inclination 

 to the blades makes a current very slow, while the maximum in- 

 clination creates a current like a mill race. The length of the blades, 

 the amount of taper from base to apex, and the height of the blades 

 in the water cause different effects in the character of the current; 

 for example, the relations of the rotary and the upward components 

 of the current can be thus controlled and varied within wide limits. 

 By these and other variations the fry can be made to scatter evenly 

 at all depths and distances from the center or to occupy various zones 

 or strata. Experience and judgment must decide the question of 

 optimum current at each particular phase. In general, it may be said 

 that a gentle, even, current made by a long, well-tapered blade and 

 slight angle of inclination is usually best. 



Containers for eggs and fry. — When the rearing was done in canvas 

 bags the old lobsters were confined in crates suspended in the bags, 

 because, if let loose in the bottom, they were apt to tear the canvas. 

 The crates were necessarily less spacious and had the objection of 

 being in the way of the newly-hatched fry, which were sometimes 

 swept against them with considerable force by the current. To the 



