AMPHIBIAN AND INVERTEBRATE DEVELOPMENT 97
As observed during amphibian metamorphosis, the two proteinases
do not show identical behaviour. Both are present and remarkably
active during larval growth, but during metamorphosis the activity of
acid proteinase continues to increase slightly, while alkaline proteinase
activity practically ceases.
Amylase activity is low but constant during larval development and
falls to an even lower level during metamorphosis; logically it can be
assumed that both alkaline proteinase and amylase participate in the
functions of the gut. The only difference is that after hatching amylase
activity is resumed but at a low level, whereas there is no alkaline
proteinase activity. Taking into account the differences in the zoological
classification between Anura and insects, it is interesting to note that
the activity of these hydrolases follows a similar pattern, from the metabolic and biochemical viewpoints, in both groups. Interesting results are
anticipated from experiments to be made on the same materials in
order to determine whether different substrates account for different
results. Changes in enzyme activity and chemical composition during
the metamorphosis of insects is dealt with more fully by Russo-Caia
(1960a) and Gilmour (1960), who provide an exhaustive review of the
literature on the subject.
IV. Results and Conclusions
A few comments should be added to those already made on the results of these enzymological studies on the embryonic development of the
amphibians and of a few invertebrates.
Our intent was to demonstrate, through these data, what support
comparative methods can give to research of this kind. However interesting the results, an enzymological analysis limited to one zoological
species, necessarily leads to partial conclusions; generalization of the
results and greater insight into these problems can only be attained by
extending the analysis to other species, more or less closely related within
zoological taxonomy (Baldwin, 1937).
In the amphibians, the degree of hydrolase activity and the class of
enzyme involved appears to vary from species to species: this is schematically shown in Figs. 10 and 11. On the whole a clearly defined picture
is obtained for lipases but the lipase activity of Bufo vulgaris does not
follow the characteristic pattern shown by the other anura studied.
The choice of enzymes, as indices of zoological specificity, might be
questioned. In fact, the origin of the enzyme has no bearing on its
specific action: thus in the most widely different organisms, amylases
hydrolyse starch; casein is digested by both animal and vegetal proteases. Our studies were concerned with given stages of development, and
As observed during amphibian metamorphosis, the two proteinases
do not show identical behaviour. Both are present and remarkably
active during larval growth, but during metamorphosis the activity of
acid proteinase continues to increase slightly, while alkaline proteinase
activity practically ceases.
Amylase activity is low but constant during larval development and
falls to an even lower level during metamorphosis; logically it can be
assumed that both alkaline proteinase and amylase participate in the
functions of the gut. The only difference is that after hatching amylase
activity is resumed but at a low level, whereas there is no alkaline
proteinase activity. Taking into account the differences in the zoological
classification between Anura and insects, it is interesting to note that
the activity of these hydrolases follows a similar pattern, from the metabolic and biochemical viewpoints, in both groups. Interesting results are
anticipated from experiments to be made on the same materials in
order to determine whether different substrates account for different
results. Changes in enzyme activity and chemical composition during
the metamorphosis of insects is dealt with more fully by Russo-Caia
(1960a) and Gilmour (1960), who provide an exhaustive review of the
literature on the subject.
IV. Results and Conclusions
A few comments should be added to those already made on the results of these enzymological studies on the embryonic development of the
amphibians and of a few invertebrates.
Our intent was to demonstrate, through these data, what support
comparative methods can give to research of this kind. However interesting the results, an enzymological analysis limited to one zoological
species, necessarily leads to partial conclusions; generalization of the
results and greater insight into these problems can only be attained by
extending the analysis to other species, more or less closely related within
zoological taxonomy (Baldwin, 1937).
In the amphibians, the degree of hydrolase activity and the class of
enzyme involved appears to vary from species to species: this is schematically shown in Figs. 10 and 11. On the whole a clearly defined picture
is obtained for lipases but the lipase activity of Bufo vulgaris does not
follow the characteristic pattern shown by the other anura studied.
The choice of enzymes, as indices of zoological specificity, might be
questioned. In fact, the origin of the enzyme has no bearing on its
specific action: thus in the most widely different organisms, amylases
hydrolyse starch; casein is digested by both animal and vegetal proteases. Our studies were concerned with given stages of development, and