8o MAYNIE R. CURTIS. 



yolks are smaller than those of succeeding eggs since at this 

 period the successive yolks are increasing in size. 



Table IV. shows also that in all cases the absolute weight of 

 both albumen and shell is higher in double-yolked eggs than in the 

 mean of the next ten normal eggs, but in none of the double- 

 yolked eggt observed was the percentage of either albumen or shell 

 as high as in the succeeding normal eggs. These observations 

 are in agreement with those on the eggs of 65 K (see Table II.). 

 They show that while an increase in the stimulation causes an 

 increase in the amount of secretion the increase is not in direct 

 proportion to the weight of the substance causing the stimulation. 



This may be due to the fact that the effective stimulation is 

 not directly proportional to the weight. That is, it may be 

 due to the size of the area of contact, or to the time the stimulus 

 is applied to each successive area of the secreting membrane. 

 Or again it may be due to a deficiency of material available for 

 the formation of the secretion, or of time necessary for its elabo- 

 ration. 



In this connection attention should be called to two facts 

 noted in previous paragraphs, first that when the eggs have 

 separate chalazal membranes the chalazae of the second yolk 

 are usually much less developed than the first, and second that 

 when the eggs have separate thick albumen envelopes the one 

 surrounding the second yolk is more viscous but forms a thinner 

 layer. In such cases at least the two yolks represent successive 

 stimulations rather than a single intensified stimulation, and 

 the glands are evidently not in a condition to respond in the 

 same degree to the second stimulation. There is, of course, 

 the possibility that the diffeience in the quantity and quality 

 of secretion in the two cases may in part be due to the fact that 

 the second yolk is moved more rapidly than ihe first but this 

 theory would not account for the smaller per cent, of albumen in 

 double-yolked eggs where the two yolks have common albumen 

 envelopes. 



The processes which determine the quantitative relationship 

 between the yolk and albumen and between yolk + albumen 

 and shell are too complex for solution with our present knowl- 

 edge. Yet it is certain that although practically doubling and 



