34 THE DEVELOPMENT OF THE SALIVARY GLANDS IN MAN 



teenth figures, the submaxillary and the anlage in question are shown, 

 and their narrow portions point in opposite directions. The legends 

 do not inform us of the orientation of the models, or of the side of the 

 embryo from which they are taken. Of course the ducts of both 

 parotid and submaxillary must point craniad from their inception, 

 while the narrow portion of the orbital inclusion has an opposite 

 direction, so that it seems not impossible that here again there has 

 been confusion between the two derivatives of the buccal sulcus. 



5. His. Embryo Zw., listed as between 15-22 millimeters. The 

 series contains 730 sections, 0.02 millimeter in thickness. The parotid, 

 which is established later than the submaxillary, earUer than the 

 sublingual, is represented by a solid sprout (Zellenknospe). It arises 

 from the buccal sulcus at a point where the sulcus appears to alter its 

 direction suddenly. In the accompanying cut it is represented as a 

 retort-shaped solid object, directed ventrad with a slight inclination 

 laterad. The attachment is fundal. 



The buccal sulcus changes its direction rather abruptly a short 

 distance caudal to the angulus oris, and again more gradually in the 

 entomasseteric portion of its course. (Cf. Fig. 4.) His's illustration 

 {Anal, menscli. Emb. Ill, Fig. 65) leaves no doubt that the reference 

 is to the former bend. 



6. Hammar. Embryo of 17 millimeters length. The fold previously 

 described (embryos i and 3) is constricted off from the oral cavity in 

 the greater part of its extent, "so dass sie als ein Lange des Bodens 

 der Wangenrinne (sulcus buccalis) verlaufendes Rohr, Ductus Ste- 

 nonianus, hervortrit." 



Again the description tits the orbital inclusion at a period in develop- 

 ment prior to its complete separation. 



7. Columbia Collection, No. 325. Length 20 millimeters, N.B., 

 measured after fixation in formalin. Obtained by Professor W. J. Mac- 

 Callum. Preservation good. This embryo presents a small parotid, 

 though its submaxillary is of a size equal to that described in other 

 human embryos of about its length. In the lateral view of the recon- 

 struction of this embryo (Fig. 5) the sulcus buccalis ascends gently from 

 the angulus oris for the greater part of its extent, to terminate by a rather 

 abrupt descent a short distance in front of the first entodermal pouch, 

 where it approaches the sulcus lingualis. It is confluent with a sulcus 



