68 THE YOUNG OF THE CRAYFISHES ASTACUS AND CAMBARUS 



old but also that these eggs would develop after union with males of the same 

 age, union which moreover took place in the previous autumn so that these ex- 

 periments also showed that the sperm got in the autumn and kept all winterwould 

 fertilize the eggs, i)artlienogenesis being, supposedly, out of the question. In 

 Astacus, Chantran stated that the eggs were laid only ten to forty-five days 

 after union but in Cambarus affinis as many as 230 days may ela]>se. The 

 data on which the conclusions rest are as follows. A crayfish 62 nun. long laid 

 eggs when forty-seven weeks old, and these eggs hatched eight days after the 

 mother's birthday; this female received si)erm the preceding autumn from a 

 male of like age and after that was kept isolated. Three other females were 

 su]i]ilied with sperm in the autumn and laid eggs in the sjiring when one year 

 old and kept isolated from males. Another female 57 mm. long laid eggs May 

 26, 1904, when one year old, having hatched May 18, 1903, and after being kept 

 isolated after conjugation with a male of like age in the autumn of 1903. An- 

 other female only 50 mm. Iiuig laid eggs when about eleven months old, April 

 29, 1905. 



It thus seems demonstrated that a crayfish growing the first sununei' to 

 the length of about two inches and receiving sperm from a male of like age 

 in the autumn may lay fertile eggs the next si)riiig when scarcely a year old. 



When older, l(i months old and about three inches long, that is in the sec- 

 ond autumn of their lives, crayfish were seen to conjugate and to lay fertile 

 eggs the following spring when two years old. In one case it was shown that 

 a female which laid eggs when 62 nun. long and not quite one year old again 

 laid eggs the next spring when 80 nun. long and but a few days over two years 

 of age. 



Though it is ))ossilile that artificial conditions may have made these cray- 

 fish that reproduce when a year old precocioiis, it is probable that this Cam- 

 barus comes to sexual maturity much sooner than does the Astacus of Europe 

 of which both Soubeiran ('65) and Chantran ('70) state that it reproduces first 

 in its fourth year, though the latter says the males were ready for conjugation 

 at the beginning of their tliird year. 



The fact that one female Ca»ibarus affinis laid in two successive years is in 

 contrast to the statement credited to Steffenberg ('72) that the female Astacus 

 in Sweden hiding away during the winter, if fecundated, breeds only every other 

 year. 



It is finally to be noted that not only did the young of C. affiHi.'i reared in 

 captivity lay fertile eggs but the young of the next generation also, so that there 

 would seem to be no obstacle to the establishment of a ]>crmanent race of domes- 

 ticated cravfish bred in caiitivitv. 



