10 
a comparison of the regenerative processes in the normal and de- 
capitated larvae. 
The decapitated larvae selected for the experiments were about 
18 mm. in length at which stage the second gills possessed four pairs 
of filaments. The gills were then cut off and a sketch made to show 
the position of the filaments. 
The growth of the gills in the decapitated larvae is somewhat 
slower on the average than in the normal. About 15—16 days elapse 
from the time of the appearance of the middle gills before the normal 
larva possesses four pairs of filaments. In the decapitated four pairs 
are not present until some 18-19 days after the appearance of the 
middle gills. 
In the time of appearance and the position of the filaments there 
is about the same variation in the decapitated as in the normal. The 
first filament appears on the posterior-ventral surface of the middle 
bar and soon after a second filament appears on the anterior ventral 
side giving rise usually to a bilaterally symmetrical pattern. Fre- 
quently these buds form at different levels and an unsymmetrical 
pattern results. About 60 to 65 hours later a second pair forms mid- 
way between the first pair and the base af the gills. They are usually 
opposite, but sometimes they are not. The third pair of filaments 
shows more variation both in time of appearance and point of origin. 
Usually they appear about 50 hours after the second pair. They may 
appear some hours earlier or later. Their position may be either 
opposite or remote from each other. The fourth pair usually appears 
about 50 hours after the third. These, like those of the third pair, 
are most frequently opposite; sometimes but a single filament is 
formed. This may form between the second and third pairs. Again, 
the filaments of the third and fourth pair may both be irregularly 
placed and arise at such times that it is difficult to say what fila- 
ments belong to either the third or fourth pairs. 
The above observations show that in the decapitate there is on 
the whole more irregularity in time and point of origin of the filaments 
than in the normal. The results need not be recorded in detail and 
may be summarized as follows: The gills regenerate completely. In 
the regeneration both the pattern and sequence in general follow that 
of the normal larva. 
