Observations on the relation of carbon dioxide and oxygen to the development of certain amphibian embryos

Abstract

The following observations were made during the past two seasons upon material kept for other purposes. 1

Eggs of all the species mentioned below were placed when fresh or in early cleavage in artesian water containing 1.32 per cent. of CO₂, the amount normal to large open ponds here being only about 0.04 per cent.

Ambystoma punctatum.—Development was at the normal rate with no mortality of embryos traceable to the CO₂ in the water. The larvæ likewise lived fairly well, though in many cases not so well in the CO₂ water as in pond water.

Spelerpes bilineatus.—Cleavage and later development were probably at the normal rate, but there was a large mortality percentage in standing or running artesian water. The mortality was less in standing water from ponds but thoroughly oxygenated water comparatively free from CO₂ was necessary to get the highest percentage of developing embryos.

Bufo 1entiginoszu.—Only a small percentage developed at all and none beyond early cleavage.

Hyla versicolor and Hyla Pickeringii—A few went through cleavage but none beyond.

Rana pipiens (?).—Mortality was very large during early stages but perhaps 5 per cent. developed until the embryos were considerably differentiated and about 3 mm. in length. None developed further. In two of the ponds observed all the eggs and embryos of this species died much as those placed in CO₂ water in the laboratory. These were ponds practically without aquatic plants and containing great quantities of decaying leaves and other plant debris and therefore doubtless had much CO₂ in the water.

Rana sylvatica.-The development was apparently at the normal rate. In many cases the larvze hatched, but though active for a day or two and clinging to the jelly mass and sides of the jars in the usual fashion took no food and developed no further.