418 MALL. [Vou. XII. 
lasting five days. She passed her next period and on December 
18th aborted the ovum.” } 
The ovum was hardened in strong alcohol without opening 
it first, and when it came into my hands its dimensions were 18 
a 
Om 

win og 
Fic. 16. — Outline Drawing of a Sagittal Section of the Model of Embryo No. XII. Enlarged 50 
times. The heavy line is the aorta. The muscle plates are numbered for occipital, cervical, and 
dorsal regions, respectively. ‘The mesoderm is striated. am, amnion; a, border between 
fore-brain and mid-brain ; x and x’, extent of closure of spinal canal; S, Seessel’s pocket; 
ch, chorda; 4' and 4”, first and second branchial pockets; 0 v, otic vesicle ; #z, mouth; 7, 
thyroid; /7, pericardial space; £2, pharynx; ez, entoderm ; S 7,septum transversum; J, liver; 
mc, neurenteric canal; ad/, allantois. 
X 18 X 8 mm., that is, it was slightly flattened. It was com- 
pletely covered with long villi. It was carefully opened, care 
having been taken not to injure the embryo in any way. The 
1 Letter from Dr. Ellis, Jan. 7, 1894. 
