DEVELOPMENTAL CHANGES IN THE VIABILITY OF SQUID EMBRYOS AFTER SUBJECTION TO CYANIDE

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Abstract
The killing exposure to 0.001 N cyanide gradually shortens from more than 20 hrs. in early embryos of Loligo peali to 15 mins. in organisms examined 4 days after hatching. It is less than 1 min. in adults. Cyanide brings about at least a 95% inhibition of the rate of O2 consumption of squid embryos at all stages examined. This inhibition develops immediately upon the addition of cyanide to the organisms. The ability of squid embryos to withstand partial pressures of CO2 up to 45 mm. Hg. was also examined. In general, this ability too decreases as the embryos become older. The effect of CO2 is almost certain to make the hemocyanin of the blood incapable of carrying O2. It may be inferred that embryos are much more resistant to lack of O2 than are adults. This general situation has been reported for certain other organisms. In the case of squid, it is now evident that this change in resistance to asphyxia is a gradual process which is not related to any particular phase of development.