62 



REPOET OF COMMISSIONER OF FISH AND FISHERIES. 



of the twin character or having more than the normal number of 

 organs. It is conceded that monsters can be produced in the eggs of 

 chickens by injury to the eggs at a certain critical period, but it is 

 held by some embryologists that they are also likely to be produced by 

 more than one spermatozoon entering the egg through the micropyle 

 at a time when sufficient water has entered the egg through its mem- 

 branes to lift them from the disk. 



The first experiments were with the view to producing monsters 

 by injury to the egg. For this purpose a half ounce of eggs from a 

 given lot was placed in a strong 4-ounce glass jar, which was then 

 half filled with water and securely corked. It was then dropped ten 

 times into a w^ooden pail, half filled with water, from a height of 4 

 feet, striking the bottom of the pail with considerable violence. Nine 

 lots were subjected to this treatment, commencing with the first lot 

 half an hour after impregnation, the second lot an hour later, and from 

 then once an hour until they had all been handled. After the eggs 

 had been forty-eight hours in running water, 100 of each of the nine 

 lots were examined under the microscope, and only one twin disk was 

 found, and that not well defined, showing that injury had not caused 

 the monstrosity to any extent. The experiment resulted, however, in 

 what to the writer was a most startling discovery. Five lots of 100 

 each, taken from the same lot from which eggs for the experiments had 

 been procured, showed but 3.4 per cent unimpregnated eggs and but 

 few ruptured yolks, while those subjected to the injury process showed 

 large numbers that appeared unimpregnated, the disk being hemi- 

 spherical, semitransparent, amber-colored, and devoid of all appear- 

 ance of segmentation. It is certain that all of these eggs were dead. 



The following table shows the number appearing normal, number 

 with ruptured yolks, and number having the appearance of being 

 unimpregnated : 



Character. 



30 min- 

 utes. 



hours. 



2i 

 hours. 



hours. 



hours. 



hours. 



65 



9 



26 



6^ 

 hours. 



n 



hours. 



8i 

 hours. 



Eggs, normal 



' 36 



57 



7 



53 

 36 

 11 



61 



27 

 12 



64 

 15 

 21 



66 

 12 

 22 



66 



8 

 26 



1 



89 

 3 

 8 



88 



Eggs, ruptured yolk 



Eggs, unimpregnated . . . 

 Twin disks 



3 

 9 





















One twin disc was also found among the five lots of eggs which had 

 not been submitted to the injuring process. In another experiment 

 eight lots of eggs were given ten shakes each with as uniform force 

 as possible with the right arm. The results were substantially the 

 same as in the above, with the exception that there were more ruptured 

 yolks than in the former case. There is obviously but one conclusion 

 to be drawn from these experiments, and that is that the larger portion 

 of the eggs which seemed under the microscope to be unimpregnated 

 were really fertilized, but that segmentation had been arrested as a 

 result of tlie injuries received. If this be true, it demonstrates that 

 in many instances where eggs have been thought to be unfertilized they 



