CYCLOPIA IN THE HUMAN EMBRYO. 15 



also made profile outlines of the two sides of the specimen, being careful to have 

 them in geometrical projection. The branchial region of the two sides of the 

 head were then very carefully drawn. These drawings are reproduced in plate 1, 

 figures 2 and 4. The specimen was dehydrated by placing the entire specimen 

 in several grades of alcohol. It was opened a year later, January 1913, at which 

 time the photographs were made. The specimens were prepared for embedding in 

 February 1914. At this time the embryo measured in absolute alcohol GL 8.6 mm., 

 CR 6.5 mm. In xylol the GL measurement was reduced to 8.2 mm. It remained 

 in several changes of xylol for 30 minutes and then was rapidly transferred through 

 several dishes of paraffin, the entire time of this operation being one hour. The 

 aim was to embed the specimen as quickly as possible in order to avoid any undue 

 shrinkage. It was then cut into transverse sections 20 /j. thick. These were 

 stained upon glass slides in hematoxylin and Congo red. It was now found that 

 we had an unusually good series of practically prefect sections, none of them 

 being distorted. Many cell divisions were found in the tissues of different parts 

 of the embryo. We now readily realized the condition of the head, as we found 

 in the sections a perfect series of an exquisite cyclopean embryo. A month later 

 the half of the chorion which was removed to expose the embryo was also cut into 

 serial sections 20 M thick and stained with hematoxylin and eosin. Further exam- 

 ination of the part of the chorion from which the embryo was peeled showed the 

 amnion close to the chorionic wall, at the point where the cord had been cut. At 

 the point of juncture there is no complete cord, but in its place are numerous 

 single blood-vessels, making the chorionic attachment of the cord appear like the 

 hairs of a camel's-hair brush. This part of the chorion was now stained in toto 

 with alum cochineal and cut into serial sections, in order to determine the exact 

 nature of the tissue of the cord as it spreads out into the chorion; for the anomaly 

 here seen had not been encountered by us before. 



A superficial survey of the villi of the chorion shows it to be apparently normal, 

 but the interior of the ovum, on account of the great amount of magma encircling 

 the embryo, indicates that the ovum is pathological. Furthermore, the chorion 

 is much too small for a normal embryo of this size. As a rule, pathological embryos 

 are contained in ova which are larger than normal. The attachment of the cord 

 to the chorion is also anomalous and a superficial glance at the head of the embryo 

 shows that it is atrophic. The whole front of the head is occupied by the mid- 

 brain. There is no lateral bulging to correspond with the cerebral vesicle. The 

 small pigmented eyes are buried deeply in the head and there is a pronounced 

 frontal process in front of them. On the right side of the head, just in front of 

 the eye, was a small protruding villus-like body which subsequently proved to be 

 the snout (plate 1, fig. 2; plate 2, fig. 7; and plate 3, fig. 5). A more detailed 

 description of the anatomy of the eye region will be given in considering the sec- 

 tions of this specimen. In order to interpret the sections properly a plaster-of- 

 paris model of the brain and head was made at a scale of 50 diameters. Later it 

 was found that this model was on too small a scale to include the muscles of the 

 eye, and a second model of the eye region was made at a scale of 100 diameters. 



