( 319 ) 
area must be equivalant to 2 &+3y. As however in this special 
case experiment „teaches that 2 (2k +y)=2k+3y, it follows that 
y=2k. 
In fig. 18 this has been represented, and in the same way as 
for fig. 16 the curves of sensibility are traced above each dermatoma. 
From the addition of these curves the curve of sensation along the 
mid-ventral line has been deduced (fig. 18 C). Here again the upper 
curve presents a schema, that may be further controlled by experiments. 
Towards the mid-ventra! line therefore the ranging of the derm- 
atomata is different from their ranging towards the mid-dorsal line. 
There the first is placed against the 3rd, the 24 against the 4th etc. 
Dog I however teaches us something more. 
The sensible area on the back has its origin in two central areas 
it is therefore %/3 central area =- 4.6. The dorsal central area is 
therefore = 2.7 c m. 
The sensible area on the abdomen is 2k+y=4k=3.2 cm. 
The ventral central area therefore is 0.8 c.m. The insensible area 
is=2k+3y=8k=6.5 om., the central area thus being again 
== (0.8 em. 
The ventral central area is therefore midling between 1/3 and 1/4 
of the dorsal central area. On dog I the situation of central and 
marginal areas may thus be easily described for a special case. 
Fig 19 represents the ranging of the central areas. 
Fig. 19. Ranging of the central areas in the special case of Dog I (fig. 16). 
Ventral central area=_0.8 cM = ky 2ky +y=3.2, Pawn ee TTD 
y = 1.6eM, 
Dorsal central rae 2. 2.7 e.M = ka 
= 0.9 cM. y 
Qx-+ 3y = 4.6 2x-- y= 2.8 cM. 
ry eM. (See text) 
