DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 1 93 



253. 257> 276. 



The measurements are vertex-breech, taken after fixation, for which 

 in almost all cases Zenker's solution was used. In certain stages, 

 where the embryos are numerous, a considerable range of develop- 

 ment is presented. The embryos of 12 millimeters, for example, form 

 a small series in which the inception of the parotid fold can be followed 

 in minute detail. Such small discrepancies are in part due to the 

 variations in the degree of flexure of the head, which causes embryos 

 of the same general development, or even litter mates, to differ slightly 

 in length. In the second place, the embryos are rated in millimeters 

 and half millimeters only, and consequently are entitled to show dif- 

 ferences in the same rating. This renders a precise chronology of details 

 rather difficult ; in general I have based my statements upon the average 

 of a group, or have simply noted the earhest and latest period at which 

 a condition was observed. That the processes are themselves variable 

 in rate to an appreciable though not large degree, is shown not only 

 by differences between Utter mates, but also by discrepancies in the 

 relative size of the several glands, even on opposite sides of the same 

 embryo. 



For the purpose of demonstrating the relation of the anlages to the 

 oral cavity, wax reconstructions were made by the usual method. As 

 the anlages are solid, the ectal surface of the epitheUum was followed. 

 Relative to the mouth the anlages are very minute in their early stages. 

 Consequently, a model of moderate magnification (40-100 diameters) 

 shows little more than their position. In order to demonstrate their 

 details, it was necessary to reproduce them on a scale of 600 diameters. 



