246 CAROLINE M. HOLT 
TABLE 3 
Giving number of mitral cells*in one olfactory bulb of the albino rat 
Arranged according to bulb weight 
RAT AGE BODY BRAIN | WEIGHT! NO. MITRAL 
LENGTH|WEIGHT| 1 BULB CELLS LEER NESS 
days mm. grams | grams 
X; Control.....) 30] 101 | 1.338] 0.017} 71,914 | Very incomplete. Up to 
point of union with cere- 
bellum 64,470 cells, cross 
section 
By Mest. cee 62 | 138 | 1.547) 0.020) 71,527 | Sagittal section 
Gerlest sete 59 | 142 | 1.482) 0.022) 79,165 | Sagittal section 
Q; Control 30 97 | 1.316] 0.024) 82,192 | Probably about 300 more 
cells. Cross section 
C@emlestveca. oe 59 | 150 | 1.578) 0.024) 70,625 | Sagittal section 
M, Test... 62 | 109 | 1.461} 0.025) 76,611 | Cross section 
Ger Testes). 759 61 | 136 | 1.456) 0.027) 83,974 | Sagittal section 
Op Restidn aa: 115 | 121 | 1.556} 0.029} 71,663 | Sagittal section 
Gs Control..... 61 | 166 | 1.630) 0.031] 81,638 | Cross section 
BeiControle ss. 61 166 | 1.698} 0.032) 71,468 | Sagittal section 
C; Control..... 62 | 174 | 1.709) 0.036) 79,839 | Sagittal section 
M; Control.... 62 | 169 | 1.711] 0.037] 76,596 | Cross section 
X- R. C. Test..! 134] 193 | 1.927] 0.040} 80,114 | Up to point of union with 
cerebrum 73,950 cells, 
cross section 
O; Control.....; 115 | 175 | 1.792] 0.041] 72,333 | Sagittal section(X, omitted 
from average) 
Average..... 76,749 
Standard deviation ¢ = 4564 
Probable error of the mean +855 
Through the middle region only every twentieth section was counted 
as the sections were extremely uniform. Through the two regions 
between this middle portion and the ends in which all cells were counted 
the mitral cells for every tenth section were counted. 
Bulb Cs, test, defective diet series. Fifty-nine days. Sagittal 
sections. Mitral cells counted for all sections at both ends of the 
series and every fifth section of the rest of the series. 
Bulb Mg, test, defective diet series. Sixty-two days. Cross sections. 
Mitral cells were counted as in Q;. Count was made also of all cell 
elements in every alternate section in the gray layer back to the anterior 
end of the cerebrum. Computation was made for entire series. 
Bulb G3, test, defective diet series. Sixty-one days. Sagittal 
sections. Mitral cells were counted for all sections at ends of series 
and for every tenth between. The computed result was 95,993. The 
middle sections between every tenth were then counted, giving a 
