THE EMBRYOLOGY OF THE HONEY BEE 97 



(1870) and Kowalevski (1871), which represent the embryos of 

 different stages surrounded by the chorion, show that they ob- 

 served these changes precisely as they are described above. 



2. The Development of the Embryo 



In the study of any developmental processes a knowledge of the 

 end stage is necessary to an intelligent comprehension of the 

 earlier stages, since these are only isolated examples chosen from 

 what is in reality a continuous process leading to the end stage. 

 This is, in a sense, their goal, but in a larger sense is itself only 

 a more or less arbitrarily chosen stage in the continuous process 

 of the life cycle. The end stage of the development in the egg is 

 of course attained when the embryo breaks the egg envelope or 

 chorion and becomes a larva. This stage, Stage XV, reached in 

 from 74 to 76 hours after the egg is laid, is illustrated by figure 

 XV, representing a recently hatched larva. This larva is drawn 

 not from a living specimen, but (like the others of this series) 

 from one which has been stained, cleared and mounted. The 

 body wall is represented as much more transparent than it is in 

 reality, in order to show more clearly the organs contained within, 

 while the sharpness of outline of these is exaggerated. 



The larva as a whole is long cylindrical in form, slightly bent 

 toward the ventral side, like a bow, and tapers gently toward 

 the caudal extremity, which is obliquely truncate. The larva is 

 divided by constrictions into a short and rounded head and thir- 

 teen segments, the latter being approximately equal in length and 

 collectively constituting the trunk. On the dorsal side the con- 

 strictions are narrower and deeper than on the ventral side. The 

 head is of the same diameter as the anterior part of the trunk, 

 and the constriction separating the two is only a trifle deeper 

 and broader than those separating the trunk segments. On the 

 ventral side of the head is the mouth (Mth). In front of the 

 latter and directed downwards is a blunt rounded lobe, the labrum 

 (Lm), while bounding the mouth laterally are two pairs of rather 

 large papilliform processes, the mandibles (Md) and the first max- 

 illae (iMx). At the rear the mouth is bounded by a single flat 

 lobe, the labium (Lb). 



The alimentary canal is simple, consisting of a tubular oeso- 

 phagus (Oe) which extends scarcely beyond the neck and opens 



