474 OSCAR RIDDLE 
the former being robbed more rapidly of their fat than of their 
protein. Now a layer of white yolk is produced in the egg. 
In fig. A is shown a diagrammatic representation of how these 
fluctuations in the quantity of food-products of a fatty nature in 
the blood-stream would effect changes in size in oil drops, if these 
latter were separated from the blood by thin and semi-permeable 
membranes—the conditions existing at the surface of an egg. Sec- 
tion A represents growing conditions—predominance of fat syn- 
thesis due to rapid ingress of the constitutents of fat. Section B | 
A 
Text Figure A=] 
Idealized representation of the relations of the periphery of a mature sauropi- 
dan egg to the blood and lymph. Follicular cells not shown; these considered per- 
vious as vitelline membrane, or by their intercellular spaces offering free access 
of lymph to that membrane. A = optimum growth conditions. B = metabolism 
of an oil drop in equilibrium. C = impoverished blood bearing away elements of 
yolk, with extension of white yolk area at the expense of yellow yolk. 6b. cap. = 
blood capillary; v.m. = vitelline membrane; w.y. = granules of white yolk; 
y.y. = granules of yellow yolk. See text. 
stationary conditions; as much of fatty ingredients is being given 
off into the blood, as is being taken from it. Section C droplets 
reduced in size as a result of continued contact with a blood stream 
poor in fat. 
