. Journal of morphology. area later enclosed by this furrow has been named by Ishikawathe Keimhohlensegment or blastocoele-segment; judging fromhis figures its later history is much the same as that of the cor-responding structure, which I have preferred to call the fenestra,in Cryptobranchus allegheniensis. The only mention of similar structures which I can find in theliterature on other forms is a description by Hatta (07) of agroove which he calls the boundary groove in the gastrula ofPetromyzon. As compared with the septal furrow of Crypto-branchus this groove is greatly exagger
. Journal of morphology. area later enclosed by this furrow has been named by Ishikawathe Keimhohlensegment or blastocoele-segment; judging fromhis figures its later history is much the same as that of the cor-responding structure, which I have preferred to call the fenestra,in Cryptobranchus allegheniensis. The only mention of similar structures which I can find in theliterature on other forms is a description by Hatta (07) of agroove which he calls the boundary groove in the gastrula ofPetromyzon. As compared with the septal furrow of Crypto-branchus this groove is greatly exaggerated in Petromyzon, con-stricting the egg so that in some cases it assumes an hour-glassform. As suggested by Hatta, the boundary groove or septal furrowis passive in origin, and a product of gastrulation. Similar con-ditions have produced it in two such widely separated forms asCryptobranchus and Petromyzon; in each case the egg containsconsiderable yolk, and the roof of the blastocoele is unusually 496 BERTRAM G. SMITH. bip. vp-
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Keywords: ., bookcentury1900, bookdecade1, booksubjectphysiology, bookyear1912
