14 Journal of the Mitchell Society [August 



to the horizontal heating unit placed above the eggs and one-tenth of 

 the time to the ventilating unit in the flue. After the third day 

 slightly less of the time will the heating unit above be running and 

 correspondingly more of the time will there be ventilation supplied 

 by the heat remaining longer in the flues. This change of ratio con- 

 tinues until near the end of the hatch it has been reversed, and ventila- 

 tion is being supplied nine-tenths of the time as against heat alone, 

 without ventilation, one-tenth of the time. 



Comparison with the rate of ventilation supplied by commercial 

 types of incubators for eggs showed that all of them operated in the 

 reverse of this. The ventilation is associated with the heat in such a 

 manner that the more heat supplied the more ventilation. But the 

 amount of heat supplied is greater when no animal heat is being gen- 

 erated. Consequently, to get enough ventilation at the end of a hatch 

 when the heat requirement is least, there must be an excessive supply 

 of ventilation associated with the flow of heat throughout the whole 

 period. The author feels that this excessive ventilation throughout 

 the hatch and the consequent drying out of the eggs is the principal 

 cause of the low efficiency of commercial incubators of today. Not 

 only is the per cent of the hatches much below that obtained from 

 hens, but the weight of the chicks hatched is about twenty per cent 

 lower. 



Savannah and Sand Eidge Plant Communities. B. W. Wells. 



The habitat of the savannah community is a level non-draining 

 area with the water table at or very close to the surface. The com- 

 munity is dominated by the grass Campulosus aromaticus and species 

 of Sarracenia, especially S. flava. A majority of the species show 

 tendencies toward xerophytism. A large number are characterized 

 by radical leaves whose whitened bases join the stem 1-3 inches below 

 the surface. This character doubtless has a significance in relation 

 to fire. 



The habitat of the sand ridge community is a more or less rolling 

 area, the soil being composed of coarse sand which except at the sur- 

 face is very dark, due to humus. So clean does the rain wash the 

 upper 1/2 inch of sand that it assumes a brilliant white aspect. The 

 reflection of the heat and light from this creates extreme conditions 

 of temperature near the surface. This community is typically domi- 



