ON THE PKEIsTATAL GKOWTH OF THE HUMAIT BODY 



AND THE RELATIVE GROWTH OF THE VARIOUS 



ORGANS AND PARTS. 



C. M. JACKSON. 

 From the Anatomical Lahoratoi-y, University of Missouri, Columbia. 



With 4 Figxjkes and 6 Tables. 



Although numerous observations on various phases of the growth 

 of the human embryo and fetus are scattered throughout the anatom- 

 ical literature, they have never been collected and presented so as 

 to give a comprehensive view of the subject. It is the purpose of 

 this paper to present, in addition to the data already available, the 

 results of an extensive series of original observations. These obser- 

 vations were made primarily in order to fill some of the existing gaps 

 in our knowledge regarding this subject, particularly concerning the 

 rate of growth during the earlier months. It is now possible to de- 

 scribe (though imperfectly and still subject to correction by further 

 data) the general course of prenatal growth in the human body, and 

 in its various organs and parts. 



The material used for these observations includes 43 specimens 

 from my collection of human embryos and fetuses. The specimens 

 range all the way from 6 mm. up to the full-term fetus. Upon 32 of 

 these specimens, the observations include the total volume, and the 

 volume of the head, trunk, extremities, and of each of the principal 

 organs of the body. For supplementary data concerning human em- 

 bryos of the first month, the volumes of seven of the His-Ziegler 

 models were measured. 



For obvious reasons, the volume rather than the weight was chosen 

 for measurement in the case of the models. In the small embryos 



The American Journal of Anatomy. — Vol. IX, No. 1. 



