3i6 



H. H. NEWMAN. 



lar tissue running from the body to the yolk of the egg across the 

 pericardium. These "string-hearts" are among the commonest 

 terata to be found in heterogenic hybrids. We have no choice 

 but to conclude that, although the heart is not very close to the 

 apical end, and is ventral rather than dorsal in position, that it 



12 



is an organ of relatively high rate of metabolism and shows 

 extreme susceptibility to retarding agents. It is undoubtedly 

 true that the heart and blood vessels form an axiate system of 

 their own, which is somewhat independent of general somatic 

 axes. The attached or arterial end (ventricles) of the heart is 

 the apical point of this axis and is the part most susceptible to 

 retarding agents. When this end of the heart is inhibited the 

 whole circulatory system will be rendered functionless, though 

 the basal parts may be fairly well developed. When the apical 

 parts are only slightly abnormal the basal parts may be fully 

 normal, but when the apical parts show extreme abnormality 

 the basal parts are usually abnormal but less so than the apical. 



