Observations on the Eggs of Ambystoma Maculatum with Especial Reference to the Green Algae

Those who have observed large numbers of eggs of the spotted salamander (Amnbystorna maculatum) have undoubtedly seen many masses colored a delicate or even a vivid green. The color of these egg masses is due to unicellular green algae which thrive in the egg envelopes, eventually giving to the jelly a green appearance. Often the algal growth, especially within the innermost jelly envelope, is so dense that it is difficult to see the developing embryo. Published accounts of this phenomenon appeared first in the writings of Orr ('88) who noted the occurrence of unicellular globular green algae in the inner envelope of Ambystorna maculatum eggs. Concerning the significance of this association he wrote: "I have not discovered how the Algae enter the membrane, nor what physiological effect they have on the respiration of the embryo, but it seems probable that in this latter respect they may have an important influence." Eycleshymer ('95) noted "numbers of minute algae" in the outermost envelope of Ambystoma eggs but failed to find them in the innermost envelope. A rather vague reference to the occurrence of algae in amphibian egg envelopes was made by Lambert ('10). He observed that the "gelatinous substance surrounding frog's eggs which were developing in a laboratory aquarium . . . showed a characteristic green color. This was due to the presence of certain unicellular algae, familiar to me by reason of several season's observations." Professor Gilbert M. Smith of Stanf ord University informed me that Lambert gave the name Oophila amblystomatis to certain unicellular green algae found growing in the egg envelopes of Ambystomna, but a description of this alga has never been published nor has the name been recognized by algalogists. Storer ('25) devoted considerable space in his "Synopsis of the Amphibia of California" to a description of another algaeamphibian egg association. He noted that the inside of each capsule of Dicamptodon ensatus eggs was "lined with a coating of small rounded green algae, of sufficient density to be seen easily with the unaided eye." Storer was unable to identify the algae nor did he attempt to find out how -the algae entered the egg. He did speculate on this latter point, however, as well as on the possibility of a symbiotic relationship. Recently Henry and Twitty ('40) have indicated that the algae-inhabited eggs Storer was dealing with might actually have been those of Ambystorna gracile rather than Dicamptodon. Breder ('27) noted that Ambystoma maculatum eggs "containing algae would not hatch in the dark while those without it [algae] readily did so." She concluded that the algae probably "helps provide oxygen for the developing embryos in the presence of light and robs them of it in darkness." Richards ('40) noted that while the capsular fluid of Amblystoma punctatum' eggs does not support bacterial growth, "occasionally an alga may grow within the capsule." Showalter ('40) found non-motile unicellular green algae in salamander eggs taken from a mountain lagoon near Madison College, Harrisonburg, Virginia. He did not identify the eggs but made the observation that the larvae, a few days after hatching, ate the algae. Bishop ('41) observed: "In the eggs of both A. jeffersonianum