Scientific Proceedings. 



33 



a manner approximately normal ; again showing that the number 

 of micromeres which may come from a macromere is constant, 

 whatever the number of macromeres may be. 



12. The results stated in the two preceding paragraphs show 

 that the omission or the addition of cleavages does not alter the 

 character or localization of the egg substances and that this locali- 

 zation, when unimpeded, determines the character of the cell 

 division. 



13. Isolated blastomeres undergo partial development, each 

 giving rise only to the cells which it would form if still a part of 

 the entire egg, but the general form of the cleavage mass is entire, 

 f. e., there is no open side. 



14. A weak electric current destroys spindle fibers and astral 

 rays, or prevents their formation and thus stops mitosis. It also 

 destroys the polarity of the cell, prevents the separation of pro- 

 toplasm and yolk, and may cause nuclei to migrate through the 

 cell from one pole to another. 



15. Abnormalities of mitosis may perpetuate themselves in 

 subsequent divisions, even when the cause which first induced 

 them is removed. 



27 (170) 



Heterotransplantation of blood vessels. 

 By ALEXIS CARREL. 



[From the Rockefeller Institute for Medical Research.'] 



It is well known that the tissues of an animal do not grow or 

 grow hardly at all in an animal of another species. Nevertheless, 

 I attempted to transplant to cats, blood vessels resected from dogs, 

 with the aim of ascertaining whether the vessels in spite of the 

 toxic action of the cat's blood on the dog's tissue, could take over 

 the functions of the vessels removed. 



The method consisted of removing a segment of the abdominal 

 aorta of a cat, and of reestablishing the circulation in the lower 

 part of the aorta by interposing a segment of the jugular or car- 

 otid of a dog and suturing it to the cut ends of the aorta. 



