522 Franklin P. Johnson. 
LENGTHIN MM. Series No. LENGTHIN MM. Serres No. 
Oe MA eR ae ORE TES 256 DS Sh OR AE Se Rene ee 181 
LOR Lee a ae ee ats a 1000 A ay: RE Te a 24 
LO retour ee ee ee is tee 1322 DONS eos PRE OTE 914 
LO aera ee ee ee 819 BO oe et RR eee ee 913 
1.Qis, 2 ie eal stern ee pe aa da i ee 828 RY PARE I RE CM nik it colt ee 649 
DO ae be REE Sa ee Cee tee SET BY (ae Wig Re amare) eo bh ee 820 
DOS ON eR Vey alee eae eee 871 7 ae es Se ge ree PRT) Re a 888 
Dats Pet et ede cin Bers Rotvat ocean Ne 737 78 (incomplete series).....723,724 
The crown-rump lengths and numbers of the older embryos used 
are as follows: 
LENGTH IN MM. SERIES No. LENGTHIN MM. SERIzEs No. 
515 RE Cn (Tee, At Eee en a eat 249 20 aos wing So ee Oe Oe 203 
Ta een tart he. arititas oes pg Ole IS ae 116 BAN rere eR yee, aa eae en eee 30 
Otten Raya PE ergs 142 WA eaten do hee secant teres Woke 131 
Oe hts Ac Np eae oben te rot: 224 oY Peles ein nrreds Ine Eiat oe eps shen <A 3 315 
ON tat eases ine Oe Leyes pepe cen Ne 340 DAO eek EMy paket et een te ee ea 186 
LO as ena yet Cie dye Pe 342 ING WORM cinatee cee eee 341 
From the older embryos, the different parts of the digestive 
tract were separately removed, imbedded in paraffin, and cut in 
serial sections of 8 microns in thickness. The sections were stained 
by different methods, among which were Heidenhain’s iron hema- 
toxylin, Hansen’s iron hemotoxylin, and Mallory’s aniline blue 
connective tissue stain. Both eosin and orange G were used as 
counter stains. From the preparations thus made, certain stages 
of development were selected, and a number of wax reconstructions 
made. The models have in most cases been made to the magnifi- 
cation of 145 diameters, so as to be easily compared. However, 
in some of the gland models, this magnification was doubled, and 
in others trebled. 
GSOPHAGUS 
Early Stages. In an embryo of 7.5 mm., the cesophagus is a 
cylindrical tube of epithelium extending from the pharynx to 
the stomach. The lumen is round and relatively large at its upper 
end, but tapers gradually until at its middle it is quite small. 
Passing downward from this region, the cesophagus gradually 
increases in size and at its lower end leads into the stomach, there 
