335 



the tablet, a slit is held close to it, in such a position as to be seen, 

 projected partly on the object and partly on the tablet, and the slit 

 is then viewed through a prism. The fluorescence of the object is 

 evidenced by light appearing in regions of the spectrum, in which, 

 in the case of the rays coming through the principal absorbent, and, 

 therefore, in the case of the rays scattered by the tablet, there is 

 nothing but darkness. 



The author states that these methods proved to be of such deli- 

 cacy, that, even on an unusually gloomy day, he was able readily to 

 detect the fluorescence of white paper ; and even in the case of sub- 

 stances standing much lower in the scale, the fluorescence could be 

 detected in a similar manner. 



In conclusion, the author states that he had found the property 

 of fluorescence to belong to a peculiar class of salts, the platinocya- 

 nides, making a third instance in which this property had been 

 connected with substances chemically isolated in a perfectly satis- 

 factory way. The present instance opens a new field of inquiry in 

 relation to the polarization of the fluorescent light. 



8. " Researches in Embryology; a Note supplementary to Papers 

 published in the Philosophical Transactions for 1838, 1839 and 1840, 

 showing the confirmation of the principal facts there recorded, and 

 pointing out a correspondence between certain structures connected 

 with the Mammiferous Ovum and other Ova." By Martin Barry, 

 M.D., F.R.S., F.R.S.E. Received May 27, 1853. 



Referring to his account of the process of fecundation of the mam- 

 malian ovum and the immediately succeeding phenomena, published 

 in various papers in the Philosophical Transactions, the author calls 

 attention to the confirmation which his views have received from 

 corresponding observations made by subsequent inquirers on the ova 

 of other animals. He more particularly adverts to a recently pub- 

 lished memoir by Dr. Keber, in which that physiologist describes 

 the penetration of the spermatozoa into the interior of the ovum, in 

 Unio and Anodonta, through an aperture formed by dehiscence of 

 its coats, analogous to the micropyle in plants. 



Small pellucid vesicles, lined with ciliated epithelium and enclo- 

 sing a revolving mulberry-like object, such as the author discovered 

 imbedded under the mucous membrane of the rabbit's uterus and 

 described in the Philosophical Transactions for 1839, have been like- 

 wise observed by Keber, not only under the mucous membrane, but 

 also and most frequently in some part of the cavity of the abdo- 

 men. Keber considers these bodies to be fecundated ova. The 

 author agrees with Keber in considering them to be ova, but he does 

 not suppose them to be fecundated, nor does he think that their 

 membrane is the vitellary membrane ("zona pellucida"), which he 

 believes to have been absorbed. He considers such ova to have been 

 detached from the ovary along with their containing ovisac, which 

 in their new situation constitutes the ciliated capsule, and as they 

 present themselves in unimpregnated animals, he now believes that 

 the formation of a mulberry-like group of cells from the germinal 



