The Morphology of Cosmobia 383 



tive granules, by whatever name they may be known, and if so it would 

 seem impossible to produce true Cosmobia as the result of experiment, 

 except by the application of means that would modify the developing 

 germ. On the other hand, if this can be done, the cause would not 

 seem to be so fundamental. In the former case the only way in which 

 the matter can be investigated is by studying the results as they are pro- 

 duced by nature, and it may thus be that these unusual beings, which 

 are at the same time orderly and definite in development and structure, 

 may prove a most important factor in the solution of the great biological 

 problems.'' 



D. The hearts and the main Hood-vessels. As characteristic of this 

 entire series there are two hearts, each composed of a half from each 

 component, and placed so that they correspond to the two apparent faces 

 and not to the two components. With each of these hearts is associated 

 a pair of lungs, which bear apparently normal relations to the two 

 apparently normal hearts, but which are also made up of a lung from 

 each individual. There thus lies back of each double sternum a set of 

 thoracic viscera which, except for some slight and evidently secondary 

 deformation, look like those of a single individual, yet, by their relation- 

 ship to the two bodies lower down, are seen to be composites, each part 

 the property of two individuals. 



To analyze this in greater detail, the thoracic viscera facing the perfect 

 side consist of a heart, made up of A's right and B's left half, to which 

 are attached A's right and B's left lung. The trachea and larynx, 

 which are in their usual place with reference to this composite set of 

 organs considered as a unit, are single in appearance but formed of 

 halves contributed by each of the two component bodies. In the same 

 way, upon the imperfect side, there lies a set of viscera that consists 

 of A's left and B's right lung, the two associated with a heart composed 

 of A's left and B's right half. Between these two sets of viscera, each 

 of which is, as it were, backed up against it, lies the oesophagus, a single 

 tube common to both individuals. The vertebral columns with the spinal 

 cords, as will be remembered, are never compound in this type of Cos- 



•'It is hardly necessary to state that the above was written before the results 

 of the recent experiments of Stockaed became known. Since, however, the 

 entire paragraph was intended to awaken speculation, and not to assert a 

 dogmatic position. I have thought it best to allow it to stand as originally 

 written. The discussion of Stockard's work is given below, mainly under the 

 review of the recent literature. 



