56 Transactions of the 



It has already been mentioned that the balloon-hke vesicle was 

 connected to the rudimental embryo by a fine pedicle (Fig. 1). 

 Upon examination of the latter in water, and with a low magnifying 

 power, two thread-like shades were observed to pass through it 

 from the vesicle to the embryo, but which became so pale by an 

 addition of glycerine, as to show no particular character, when 

 examined with a higher amplification. At their entrance in the 

 embryo, however, they could be observed to communicate with an 

 opaque network, from which observation I supposed that the whole 

 was a continuation of the system of canals of the vesicle. This 

 supposition was afterwards confirmed by a closer examination of 

 small fragments of the embryo, in which I observed some of these 

 small canals, containing blood corpuscles. The embryo itself con- 

 sisted of fine granular fibrillse, arranged in plexus -like bundles, the 

 interspaces being filled with a considerable number of embryonic 

 nuclei and numerous granules. Besides these elements a number of 

 large hexagonal cells, and certain free nuclei were still observed on the 

 margin of the embryo. This whole mass of fibrillse, granules, nuclei, 

 &c., &c., representing the rudimentary embryo, was situated between 

 the two layers of the ovum. The interesting results of a careful 

 examination of the latter with their appended villi, as well as of the 

 process of multiplication of the nuclei, met with in this ovum, I 

 must forego for the present ; in my treatise on the formation and 

 development of the embryonic blood-vessels, I shall discuss them 

 more in detail. 



Whether this embryonic mass of fibrils, granules, nuclei, &c., &c., 

 represented the remains of an embryo, stunted in its growth, or 

 only a single part of it thus far developed, it would be difficult to 

 decide. As I had hitherto no opportunity of examining practically 

 of my own accord the ovum in its earliest stages of development, I 

 feel some delicacy in attempting to give a solution of the pheno- 

 menon, and I am all the more anxious to learn the views of more 

 experienced embryologists upon this subject. According to the 

 best of my judgment, it had not been arrested in its growth. It 

 might rather be supposed that the material, forming the area 

 germinativa, did not sufiice for the formation of the entire embryo, 

 in consequence of which only a part of it had been formed. But as 

 the umbilical vesicle especially, was so fully developed, it is not 

 impossible that the above-described mass of fibrils, nuclei, &c., &c., 

 should represent the only partially-formed alimentary canal, and 

 that, accordingly, the vegetative layer alone had taken part in the 

 formative process.* We will now return to the embryonic blood 



* I was led to take this view of the subject bj' the examination of a human 

 ovum of five weeks (according to tlie statement of the woman), in wliich not the 

 slightest trace of an embryo was to be found, although tlie appended villi were 

 well developed in form. The structure of the walls of this ovum, as well as of 

 its villi, consisted of a delicate fibrous tissue containing a groat number of oval 



