He employed incubator sncks hanging in the wr.ter nnd Inter 

 ■■Tooden inoubntor sacks idth vfindows of brass gauze for the exchange 

 of the vrutevi in these the water vras kept in constant rotating 

 motion by means of a two bladed propellorj t?ie establishment is 

 housed on a float. The results v/hich were already reached in the 

 first years induced many fishery authorities to adopt this method, 

 but everjiuhere it is again given up, or as in Holland, has become 

 modified severelye The European lobster is raised artificially 

 today only in Korway and Holland, aside from laboratory experi- 

 ments. The Dutch apparatus is, as the American, housed on a float 

 vrhich carries the brood boxes hanging in the water. Wl-iile havrever 

 the /jnerican boxes were built originally of sail cloth r.nd later 

 of wood, and had a 10 x 10 feet flat bottom and a depth of foic 

 feet, the Dutch arc made from perforated celluloid or aluminum 

 plates and have a volume of only 1,5 x 1.5 x 0»9 cubic meters* 

 Through the sma.ll box's perforated v/alls and the surface, vriiic?! is 

 greater in proportion to the volume, the pure ivater has an easy 

 entry which is of great importance for the good vitality of the 

 larvae. In all boxes a propeller di'ivon slowly by a motor rotates 

 (eight revolutions per minute). The lai-vae are obtained in a very 

 simple manner, since by putting a female bearing ripe eggs in the 

 middle of a box, one cr.n, on the following morning, fish out and 

 piit in another box the hatched out larvae v/hich seek at once the 

 surface. They must now be fed heavily, for which vr.rious animal 

 ma.tter can be employed: mussels, fish eggs (salted cod eggs> for 

 example)^ fish and crabs (for example, shore crabs). The food 

 must be ground very finely, mixed with Virater and be turned out 

 in great quantities, since otherwise the cannibalism of the larvae 

 causes a great loss. The large quantities of organic mr.tter vfhich 

 by far can not all be again provoked by the perfusion, produces a 

 heavy brovjth of bacteria, infusorians^, diatoms., etc. on the larvae 

 and on the v;alls« It is not easy here to find a correct middle 

 Virayj feeding with small living animals (for example, copepods) 

 is -without doubt the best. 



After the Aiaerican methods had been abandoned in Norway after 

 five years of unsuccessful experiiaentation, Dannevig (36) there 

 tested thoroughly a new mothodi Also mth it the motion of the 

 water rotates, but it is produced by a stream, of "v/ater opening at 

 a tangent to the bottom of the side wallo The whirling~up -rater 

 m.otion caused in this manner keeps the larvae and the food float- 

 ing and at the same time makes possible a renc/ral of the water. 



The efficiency for the methods adhered .to today is, not a^lvrays 

 essentially less than for artificial fish rearingo If one places 

 about 2,000 nev/ly born larvae per cubic meter in the brood boxes, 

 thus the average yield for the Dutch experiments is not much 

 higher than 25 per cent, tVie maximum is 65 per cent. The losses 

 for the first stage are very lav:, at the end of the second and 

 third they however become very great, for mostly entirely urOcncwn 

 reasons; here the great gap v/hich yet exists in our knowledge of 



151 



