470 RICHARD ASSHETON. 
ventral surface from before backward, although it is very 
much more rapid around the region of the future mouth. 
About the time the tadpole measures 4 mm. two curious 
areas, known variously as “ suckers,” “ Haftorgane,” “ crochet 
de Rusconi,” &c., below the region of mouth (which is now 
represented by a slight depression), have become prominent 
features, and in connection with them a considerable modifica- 
tion in the ciliation of that region occurs. 
The term “ sucker” is hardly suitable, for it seems doubtful 
whether attachment is ever in Auura effected by true suction. 
With regard to the functions of these organs, which perhaps 
might be more rightly called cement glands, Marshall and 
Bles, in their paper upon the development of the blood-vessels 
of the frog, made a suggestion which seems to me to be entirely 
unsupported by evidence. 
They wrote thus on page 215 :—“ Though the mouth is not 
yet open, the tadpole shows a distinct increase in bulk as 
compared with the 8 mm. stage. It has occurred to us as 
possible that the suckers may be used for absorbing food, and 
that in this way the increase may be explained; ... and 
sections of the sucker show that the greatly elongated and 
columnar cells of the sensory layer of the epiblast covering 
them are often produced at their free ends into protoplasmic 
processes, that would seem well fitted for absorbing the jelly.” 
The “increase in bulk” noticed by them between the 
64 mm. stage and 5 mm. stage may be as well accounted for by 
the large increase of the meshes of the mesoblast which occurs 
at this period. To effect this conversion of a compact mesoderm 
into a network of finely drawn-out stellate cells, no doubt it is 
necessary that water should be absorbed. It seems, however, 
hardly likely that absorption by the skin should take place at 
the spots where the epiblast appears four to eight times 
thicker than anywhere else. 
The true function of these organs has been correctly stated 
by Stohr (15) in these words: 
“Sie bestehen aus langgestreckten einzelligen Driisen (bei 
Bufo cinereus) die sich durch starke Pigmentirung auszeichnen 
