530 HENRY H. DONALDSON AND G. NAGASAKA 
TABLE 1 
Data on the twenty-four normal male albino rats used for this study 
NUMBER AGE BODY WEIGHT BODY LENGTH TAIL LENGTH 
days grams mm. mm. 
I 17 18.7 86 61 
II 17 18.7 88 61 
Til - 26 25.2 97 74 
IV 26 25.2 96 72 
Vv 29 43.3 122 94 
VI 29 42.8 120 88 
VII 39 59.2 130 110 
VIII 39 58.9 130 108 
IX 49 81.0 148 132 
x 49 82.0 147 126 
XI 81 115.1 168 141 
XII 81 114.5 163 140 
XIII 85 120.3 185 150 
XIV 85 117.0 185 155 
XV 104 149.3 190 158 
XVI 104 153.5 187 160 
XVII 125 178.0 194 155 
XVIII 25a 180.8 195 159 
XIX 130 233.1 212 185 
xX * ~130 228.8 217 173 
xXXI 312 243.1 219 176 
XXII 312 236.5 213 172 
XXIII 360 316.3 234 178 
XXIV 360 314.1 235 180 
attained their full size, the examination was begun with rats 17 
days of age, since at this time some of the cell bodies at least had 
reached nearly their full size. 
TECHNIQUE 
Each rat was tested while alive to make sure that it was quite 
normal in its reactions. Rats thus selected were killed with 
chloroform, and the body weight, body length, and tail length 
recorded, asin table 1. The rat was then completely eviscerated, 
as this makes the subsequent dissection easier. The spinal canal 
was next opened so as to expose the seventh cervical segment 
with its nerves, and both segment and nerves were removed. 
