76
G. REVERBERI
(c)
(d)
FIG. 23. Treatment by LiCl (Ascidia malaca), α, preparation in toto; b, c, d, longitudinal
sections. One notes the complete absence of brain (Farinella-Ferruzza, 1955).
the function of the organ. The results of the blocking of Cholinesterase
led to another speculation. If the unfertilized eggs are treated with the
inhibitors, and are then allowed to develop in normal sea-water, they
give rise to tadpoles completely normal but devoid of all motility. It
seems difficult to admit as an explanation of this result that the eggs
have retained the inhibitor during their development in pure sea-water;
probably the enzyme, though in very small quantity (undetectable by
This enzyme is localized in the musculature in Ciona. Experiments on
Giona eggs with specific inhibitors led to the formation of tadpoles which
had completely normal 'heads' and tails, the latter however, were
incapable of even the slightest movement. The consequences of the
enzymatic block, then, affect not the morphological structure but rather