American Fisheries Society. ith 



LACK OF FERTILIZATION VS. ARRESTED SEGMENTATION. 



BY J. J. STKAXAIIAX, BULLOCIIVILLE, GA. 



A series of experiments was carried on by the writer durinij;' 

 the whitetish spawning- season, with the view of discoverinjj-, if 

 possible, what causes monster embryos in fish eggs, especially 

 those partaking of the twin character or having more than the 

 normal number of ])arts or organs. 



Probablv a majority of biologists hold that these monsters 

 are occasioned by injury to the egg at certain critical periods 

 during development. In fact, it is conceded that these monsters 

 can be so produced artificially in the case of the chick, and 

 doubtless others, but it is also held by some eminent embry- 

 ologists that they may likely also be produced by more than one 

 spermatozoon entering the egg through the micropyle at a time 

 when sufificient water has enccred the egg through its mem- 

 branes to lift them from the disc. 



The first series was carried on with a view of producing 

 monsters by injury, p^r this purpose a four-ounce glass jar was 

 used. Into this one-half ounce of eggs from a given lot were 

 pkced. when the jar was half filled with water and securely 

 corked. It was then dropped ten times into a wooden ])ail half 

 filled with water, from a height of four feet, the jar striking the 

 bottom of the pail with considerable violence. 



Lots of eggs were thus treated, beginning with the first one- 

 half hour after the eggs were taken and impregnated, the second 

 one hour later and tlu n an hour up to and includiuir the ninth 

 lot 



On examining these eggs under the microscope after they 

 had been 48 hours in ruiming water, only one twin disc was 

 found, and that not very well defined, 100 eggs of each lot haviu"- 

 been examined, showing that the injuries had not caused them 

 in any considerable numbers. 



