UNFERTILIZED STARFISH EGGS. 297 



minutes on three successive clays to iooC. A female starfish 

 was thoroughly washed externally, an arm was opened, and one 

 of the ovaries removed with sterilized forceps and placed in 

 sterilized sea water. From the thick stream of eggs which at 

 once flowed out of the ovary, a few drops were quickly introduced 

 with a sterilized pipette into each of the sterilized flasks. A 

 second series of eight flasks contained normal sea \vater, and a 

 few drops of the same eggs were introduced into these flasks also. 

 A third series of flasks \vere filled with sea water, to each of 

 which were added 2 c.c. of a putrid, foul-smelling culture of old 

 starfish eggs in order to bring about a rapid development of 

 bacteria from the beginning. Each of these flasks also contained 

 eggs from the same culture as those in the sterilized flasks. 



That perfect sterilization had been attained in the first eight 1 

 flasks was proved by the fact that all the flasks remained abso- 

 lutely clear and cloudless during the course of the experiment, 

 and that three of the flasks which had not been opened are even j 

 to-day (after six weeks) absolutely clear, and every egg can be j) 

 individually recognized. The flasks containing the unsterilized sea 

 water became cloudy already after twenty-four hours, and after two 

 days the eggs had become the prey of bacteria and no individual 

 egg could be recognized. The sterilized flasks which were opened 

 were at all times free from foul odor, while the unsterilized flasks 

 gave off a penetrating stench, often after one, invariably after two 

 days. The microscopic examination of the sea water for bacteria 

 was always negative in the sterilized flasks, always positive in the 

 other flasks. In those flasks to which 2 c.c. of the putrid culture 

 of starfish eggs had been added, bacteria and infusoria were 

 exceedingly numerous from the beginning. 



Six hours after the beginning of the experiment one flask of 

 each of the three series was opened and the eggs examined 

 microscopically. The picture was the same in all three flasks. 

 Nearly all the eggs were mature, and a small number of them 

 were opaque or black. But what is of the greatest importance to 

 us is the fact that the percentage of opaque dead eggs was just 

 as great in the sterile culture (if not greater) than in the 

 unsterilized or the infected sea water. 



Twelve hours later, that is to sav eighteen hours after the 



