220 Dr Martin Barry on the 



cerning wliicli Professor Owen in a lecture remarked, •' There 

 is a close and interesting analogy between the above pheno- 

 mena, which were published in 1841, and some of those com- 

 municated by Dr M. Barry to the Royal Society, in January 

 1841, and published in the Philosophical Transactions of the 

 same year. The clear central nucleus of the blood-corpuscle 

 [see figs. 22, 23, 24, 25] is there shewn to form two discs, 

 which give origin to two cells. We may, likewise, discern 

 in the pellucid nucleus of the yolk, dividing and giving origin 

 to two yolk-cells, according to the German author, the hyaline 

 nucleus of Dr M. Barry."* 



Between the appearances presented by the mammifer- 

 ous germ during the passage of the ovum through the ovi- 

 duct and certain infusoria, including the volvox glohator as 

 figured by Ehrenberg (some of whose observations have been 

 confirmed and extended by myselff), the resemblance, first 

 mentioned by Professor Owen, is so remarkable that we cannot 

 avoid the belief, that the same process operates in both. And 

 farther, we have here a most interesting confirmation of the 

 view, that the germ of the highest animals at certain pe- 

 riods, represents, or passes through forms permanent in the 

 lowest. 



Cilia-bearing cylinders arise, not by coalescence — as sup- 

 posed by Valentin — but by division, like some of the Vorti- 

 cellae ; which they resemble also in the position of the cilia. 



I have already said that in Mammals, the rudimental em- 

 bryo is no other than the nucleus of a cell ; which nucleus 

 originally has the same appearance and undergoes the same 

 kind of changes as the nucleus of every cell subsequently de- 

 veloped from it, and entering into the formation of the em- 

 bryo. — The first portion of the embryo that is formed is the 

 chorda dor salts, corresponding to the supposed " primitive 

 trace" of authors. I have published a memoir J shewing this 



* Hunterian Lectures. 1843. P. 78. 



t See the Number of this Journal for October 1843, pp. 214-219. 



\ Philosopliical Transactions. 1841. 



