182 George 8. Huntington and Charles F. W. McClure. 
and from series 75 on, with the exception of series 474, to the 
Embryological Collection of Columbia University (College of 
Physicians and Surgeons). 
A SUMMARY OF FORMER INVESTIGATIONS BEARING UPON THE 
DEVELOPMENT OF THE MAMMALIAN JUGULAR LYMPH SACS. 
It is not the purpose of the present paper to give a complete his- 
torical review, nor a statement concerning the differences of opin- 
ion which exist at the present time in regard to the development 
of the lymphatic system in general. Both of these subjects have 
been fully considered by Huntington‘ and Sabin®, and can be 
referred to by anyone interested in the matter. 
It may be stated here, however, that all American anatomists 
who have thus far investigated the development of the mamma- 
lian jugular lymph sac, as distinguished from the general system 
of lymphatic vessels, now agree that it is derived directly from the 
venous system. It may, therefore, be of interest to examine the 
evidence upon which this conclusion was originally based. With 
the exception of the present writers, Sabin and Lewis, as far as we 
are aware, are the only investigators who have studied the develop- 
ment of the mammalian jugular lymph sacs. 
Sabin’s® original statement concerning the development of the 
lymphatic system, including the jugular lymph sacs, was as 
follows: 
The lymphatic system of the embryo pig begins as two blind ducts 
which bud off from the veins in the neck. At the very start the openings 
of these ducts into the veins are guarded by valves formed by the direction 
which the endothelial bud takes as it grows from the vein. In the ducts 
themselves there are no valves at first. From these two buds, and later 
from two similiar buds in the inguinal region, ducts grow toward the skin 
and widen out to form four sacs or lymph hearts and from these saes the 
lymphatics grow to the skin and cover its surface (page 387, 1902). 
‘The Genetic Interpretation of the Development of the Mammalian Lymphatic 
System. The Anatomical Record, nos. 1 and 2, vol. 2, 1908, pages 19 to 45. 
5Sabin, Florence R. Further Evidence on the Origin of the Lymphatic 
Endothelium from the Endothelium of the Blood-vascular System. The Anatomi- 
cal Record, vol. 2, 1908. . 
6 The American Journal of Anatomy, vol. 1, 1902; vol. 3, 1904 and vol. 4, 1904. 
