D. D. CUNNINGHAM. 
60 
being employed in the latter case^ as in the experiments on 
starvation of fungal tissues. A very large number of careful 
observations were‘made on the toad-larvae ; those on the larvae of 
the bullfrog were few in number^ and only undertaken with a 
view to compare the general results with those of the former 
series. A detailed account will therefore be given regarding the 
phenomena observed in the toad-larvae, with brief notices of 
those occurring in the others. 
Before describing the effects produced by abnormal conditions 
of nutrition it is necessary that some account of the healthy 
tissues and organs should be given. A complete description of 
the entire anatomy of the larvae would occupy much space, and 
seems unnecessary for a correct apprehension of the most impor- 
tant effects of starvation ; anatomical details are therefore given 
in regard only to the transparent portions of the tails and to 
the intestinal canal. The state of the tissues in these was made 
the object of special study in all the experiments, the tissues of 
the fin affording exceptionally favorable opportunities for obser- 
vations conducted during the life of the animals, and those of 
the intestinal canal being readily studied without the employ- 
ment of means calculated to introduce manipulative fallacies. 
The lateral portions of the tail in the larvae of Bnfo melano- 
stictus may be described in general terms as consisting of a sheath 
of epidermis containing a network of ramified connective-tissue 
elements, together with vascular and nervous structures, and a 
number of free cells or bioplasts characterised by their irregular 
ramified outline and amoeboid changes of form. A few cells 
containing pigment are also present in some cases, but their 
number and distribution are very uncertain. 
The epidermis consists of two layers of epithelial cells. In 
the outer of these layers the constituent cells are flattened, so as 
to form polygonal plates. The edges of these plates are straight, 
or at utmost only show slight shallow sinuosities (vide fig. 2, a). 
The cells vary greatly in size and form in various portions of 
the fin, but are apparently everywhere closely adapted to one 
another, forming a continuous, uninterrupted sheath over the 
deeper structures. Each cell contains a large oval nucleus, and 
this, together with the portion of the cell immediately surround- 
ing it, appears to project on the under surface of the plate. 
Due to this circumstance, whilst the external surface of the 
entire layer of epithelium is flat and smooth, the under surface is 
uneven and covered with prominences. These prominences come 
into close contact with the upper surface of the inner layer of 
epidermis, while a series of shallow spaces is left elsewhere cor- 
responding with the thin portions of the plates. 
The inner layer of epidermis differs in many respects fj-om that 
