[Comparative action of chronic injection of alpha toxin from Naja nigricolis and of botulinum toxin A on the development of chick embryo dorsal and ventral spinal roots]

The chronic injection of high doses of alpha toxin from Naja nigricollis or botulinum toxin type A in the yolk sack of developing Chick embryos causes a selective decrease of the number of fibers in the ventral roots of the spinal nerves; at the concentrations needed this reduction is more important with the alpha toxin than with the botulinum toxin.