24 E. W. SEXTON AND M. B. WING. 
the only Hybrid in it. None of the others captured then or at any other 
time have shown the red strain. 
One series of 5000 was counted, for example, and all were black-eyed. 
Considering, however, that this way of examining the eyes was not a 
sufficiently accurate test, it was decided to take two dredgings, a winter 
one and a summer one, of as many animals as could be found at the time 
in all the ditches as the result of a day’s collecting. These were to be 
counted, each one examined for eye-colour, each ovigerous female to be 
separated until its brood hatched, and each brood to be counted and 
examined. A number of adults were to be taken and mated with red- 
eyed mates, and their young examined. And finally, the most im- 
portant test of all, a number of mated pairs were to be kept and bred to 
the F, generation, to see if captivity and inbreeding would repeat the result 
obtained with the Pair I of June, 1912. 
The first dredging for this purpose was made on February 11, 1915, 
373 animals, all black-eyed, were found, 198 of which were adult females ; 
the greater part of the remaining 175 specimens were males, the rest were 
immature. Of the females, 112 had eggs, the others, 86 in number, were 
paired. 
The 112 ovigerous females were separated, and their young counted 
on extrusion. The broods in many cases were small, many of the animals 
having apparently not long reached maturity ; e.g. the first broods to 
hatch were in number as follows: 11, 3, 15, 4, 9,11. In all, the number 
of young extruded was 641, all of them black-eyed. 
Forty-six adults were mated with Red mates ; all produced black-eyed 
offspring, proving beyond doubt that they were Pure Black and not 
Hybrid. The number of broods counted was 62, the number of young 853. 
Twelve of the 86 black-eyed pairs brought in from the ditches were 
taken to breed to the second generation of offspring. Of these Pairs II 
to XII * were kept for two or three broods each, and then returned to the 
rest of the dredging. The total number of young in the first generation 
of ofispring from these broods was 473, all black-eyed. 
For the second generation, one brood from each of the Pairs II to XII 
was taken, the first to mature in each case. This was done because the 
red eyes appeared in the first brood of the first F, pair of the original 
stock (p. 22). 
When these broods reached maturity some of the mated pairs were 
separated and the others allowed to mate in the brood-bowl, the young 
in all cases being removed as soon as possible and examined for eye-colour. 
* Pair I produced no young, the female throwing off the eggs; the male was then 
paired with three other females, two Black from the dredging, and one Red from the old 
stock ; all laid eggs, but no young were hatched, and the male died. 
