It is well known that the red corpuscles of the newborn are larger than those of the normal adult. Little study has been made, however, of the size and number of the corpuscles of the fetus. The purpose of this communication is to describe certain observations on the size and number of the red cells in the blood of the fetus and newborn of several species of mammal; namely, man, rabbit, pig, rat, cat and dog. In the species examined, it has been found that low erythrocyte counts and large red corpuscles are consistently found in the fetus, and that the younger the fetus the lower is the red cell count and the larger the red corpuscles. As compared with the blood of the adult of the same species, there is in the fetus what may for descriptive purposes be spoken of as " anemia " of the macrocytic type. As the fetus develops, the erythrocyte count rises and the mean size of the red corpuscles diminishes in a manner which reminds one of the changes which take place in the blood of patients with pernicious anemia during the response to liver therapy.
REVIEW OF LITERATUREMalassez (1)