283 



by Von Baer. Farther, that the origin of the " laminae dorsales " 

 of this naturalist (the " central nervous system" of Reichert) is not 

 simultaneous with, but anterior to, that of the chorda. 



The author then reviews the observations of Rathke and Reichert 

 on the chorda dorsalis, which contain internal evidence, he thinks, 

 of a process in the development of Fishes, Reptiles, and Birds, the 

 same as that which he has observed in Mammalia ; namely, the ori- 

 gin of the embryo out of the nucleus of a cell. 



And it is his opinion that this obser^'ation may assist to solve a 

 question on which physiologists are not agreed ; for it shows, that if 

 the nucleus of a cell is a single object, the first rudiments of the 

 embryo are not two halves. The author thinks that unless the very 

 earliest periods are investigated, it is in vain that we attempt to 

 learn what that is, of which the rudiments of the embryo are com- 

 posed. From not attending to this, physiologists have supposed 

 their " primitive trace" to arise in the substance of a membrane, 

 which the author, in liis second series on the embryo, showed could not 

 be the case. To the same cause he thinks is referable an opinion re- 

 cently advanced by Reichert, that the first traces of the new being 

 are derived from cells of the yelk. 



January 14, 1841. 



Sir JOHN W. LUBBOCK, Bart., V.P. and Treas., in the Chair.^ 



Charles Enderby, Esq. and James Cosmo Melvill, Esq. were bal- 

 loted for and duly elected into the Society. 



A paper was read, entitled, " On the Corpuscles of the Blood." 

 Part II. By Martin Barry, M.D., F.R.S.S. L. and E. 



The observations recorded in this memoir are founded on an ex- 

 amination of the blood in every class of vertebrated animals, in some 

 of the Invertebrata, and in the embryo of Mammalia and Birds. The 

 nucleus of the blood-corpuscle, usually considered as a single object, 

 is here represented as composed, in some instances, of two, three, 

 or even many parts ; these parts having a constant and determinate 

 form. In the substance surrounding the nucleus, the author has 

 frequently been able to discern, not merely " red colouring matter," 

 but cell-like objects ; and he points out an orifice as existing at cer- 

 tain periods in the delicate membrane by which this substance is 

 surrounded. In a former memoir he had differed no less from pre- 

 "v-ious obser^-ers regarding " cells." He had sho^ni, for instance, 

 that the nucleus of the cell, instead of being " cast off as useless, 

 and absorbed," is a centre for the origin, not only of the transitory 

 contents of its own cell, but also of the two or three principal and 

 last-formed cells, destined to succeed that ceil; and that a separation 

 of the nucleus into two or three parts, is not, as Dr. Henle had sup- 

 posed in the case of the Pus and Mucus-globule (the only instances 



