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of ammonium sulphate (55 to 60% of saturation). Embryos after treatment for 24 hr with NaSCN develop a large notochord and more protein
is precipitated at higher concentrations of ammonium sulphate (Table 1,
on following page).
20
0
10 20 30 40 50 60 70
90 C
FIG. 25. Salting-out diagram for Rana embryos showing the difference between Litreated embryo and control (neural fold stage) (from Ranzi and Citterio, 1955).
10 20 30 40 50 60 70 80 90 C
FIG. 26. Salting-out diagram for Rana embryos showing the differences between
NaSCN-treated embryos (two different experiments) and control embryo (yolk plug
stage) (from Ranzi and Citterio, 1955).
The salting-out diagram of the embryos of the non-viable cross Bufo
viridis $ x B. bufo $ is similar to that of vegetalized embryos of the
parent species (Bufo viridis andl?. bufo) (Fig. 27). The differences between
the non-viable cross and the normal embryos of the parent species become evident during cleavage and are very marked during neurulation.
This observation seems to be very important because the developmental
stages of the non-viable cross of the toad species were not treated with