114 UTILIZATION OF MINUTE LIFE. 



experiment prescribes. That is the fundamental 

 principle of rearing Crustacea (Fig. 10). 



By breeding crawfish in this manner, some in- 

 teresting facts relating to the earlier phases of their 

 life have been brought to light. 



The common lobster (Astacus marinus) is abun- 

 dant on the rocky coasts of England, and may be 

 seen in clear water, at no great depth, at the time it 

 deposits its eggs, that is, about the middle of 

 summer. It produces from 15,000 to 20,000 eggs. 

 Dr. Baster actually counted 12,444 eggs under the 

 tail of one female lobster, exclusively of those that 

 still remained unprotruded in the body. 



The craw-fish (Astacus fluviatilis) produces up- 

 wards of 100,000 eggs, a fact which has doubtless 

 contributed to the success of the undertakings 

 alluded to above, and which seems calculated 

 to facilitate the artificial multiplication of this 

 species. 



Large lobsters are very voracious animals, de- 

 vouring sometimes their own young, and fighting 

 fearful battles among themselves. When in these 

 skirmishes they lose a claw it soon grows again, 

 but never so large as the lost one it replaces. This 

 power of reproduction of lost parts is extremely 

 developed in lower animals, where the principle of 

 vitality is not concentrated so much in central 

 organs ; it is observed to a wonderful extent in 



