The effects of inanition and The effects of inanition and malnutrition upon growth and structure effectsofinaniti00jack Year: 1925 EFFECTS ON THE HIGHER INVERTEBRATES 49 was likewise found necessary for development of the fertilized ova» Even with CaS04 and CaCl2 present in the solution, the development proceeds no further than an abnormal pluteus, with rudimentary skeleton (Fig. 22). The presence of CaC03 was found necessary, not only for the development of larvae with a normal skeleton, but also for the preservation of the already formed skeleton in em Fig. 17. Fig. 16. Fig. 18. Figs. 16
The effects of inanition and The effects of inanition and malnutrition upon growth and structure effectsofinaniti00jack Year: 1925 EFFECTS ON THE HIGHER INVERTEBRATES 49 was likewise found necessary for development of the fertilized ova» Even with CaS04 and CaCl2 present in the solution, the development proceeds no further than an abnormal pluteus, with rudimentary skeleton (Fig. 22). The presence of CaC03 was found necessary, not only for the development of larvae with a normal skeleton, but also for the preservation of the already formed skeleton in em Fig. 17. Fig. 16. Fig. 18. Figs. 16 to 25 illustrate the effects of various salt deficiencies upon the development of the sea-urchin, causing inhibition or distortion of the normal growth process. After fertilization in normal sea-water, the ova were placed in artificial media containing various salt mixtures. The normal controls in the complete salt mixtures pass through the segmentation stages, blastula (Fig. 25) and gastrula stages, reaching the normal pluteus stage shown in Fig. 16. All these figures (16 to 25) are taken from the monograph by Herbst ('97). Figs. 17 to 24 represent the most advanced stages reached in the solutions variously deficient. (After Herbst '97.) A, arms; a, a, a—segments of alimentary canal; Be, blastocele; Cc, (abnormal) ciliated crown; em, egg membrane; m, mesoderm cells; Sk, skeletal rods; Sp, 'snout-like' process; Vac, vacuoles in blastula cells. Fig. 16.—Normal pluteus stage of the sea-urchin Echinus, reared in a complete salt mixture containing NaCl, KC1, MgS04, CaSCu, CaCOs, FeCOs, and CaHP04. Fourth day. Fig. 17.—This stage of (abnormal) segmentation represents the maximum development reached in the same salt mixture as the foregoing (Fig. 16), with omission of the phosphate. Most of the ova failed to segment at all, or were arrested in still earlier stages of abnormal segmentation. This illustrates the necessity for phosphorus in normal development of the sea-urchin, E
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