382 Royal Society. 



these conclusions may have on the physiology of the iris. He thinks 

 that the phenomena of its motions can receive no satisfactory expla- 

 nation on the hypothesis of erectility alone, or on that of the anta- 

 gonism of two sets of muscular fibres ; the one for dilating, the 

 other for contracting the pupil. He is convinced that the contrac- 

 tion of the pupil is the effect of muscular action ; but does not con- 

 sider the knowledge we at present possess is sufficient to enable us 

 to determine the nature of the agent by which its dilatation is effected. 

 He, however, throws it out as a conjecture, that this latter action 

 may be the result of an unusual degree of vital contractility, residing 

 either in the cellular tissue, or in the minute blood-vessels of the 

 iris. It is from elasticity, he believes, that the iris derives its power 

 of accommodation to changes of size, and its tendency to return to 

 its natural state from extremes, either of dilatation or of contraction ; 

 but beyond this, elasticity is not concerned in its movements. 



Feb. 16. — " On Fissiparous Generation :" by Martin Barry, M.D., 

 F.R.S. L. and Ed. 



The author observes that the blood- corpuscle and the germinal 

 vesicle resemble one another* in the circumstance of an orifice ex- 

 isting in the centre of the parietal nucleus of both. He pursues the 

 analogy still farther, conceiving that as a substance of some sort is 

 introduced into the ovum through its orifice, which the author 

 terms the point of fecundation, so the corpuscles of the blood may 

 undergo a sort of fecundation through their corresponding orifice ; 

 and also that the blood-corpuscle, like the germinal vesicle, is pro- 

 pagated by self-division of its nucleus ; a mode of propagation 

 which he believes to be common to cells in general. The nucleus 

 of the germinal vesicle, or original parent cell of the ovum, gives 

 origin, by self-division, to two young persistent cells, endowed with 

 qualities resulting from the fecundation of the parent cell ; these 

 two cells being formed by assimilation, out of a great number of 

 minuter cells which had been previously formed. This account of 

 the process, which takes place in the reproduction of the entire or- 

 ganism, explains, according to Dr. Barry, the mysterious reappear- 

 ance of the qualities of both parents in the offspring. 



Certain nuclei, which the author has delineated in former papers 

 as being contained within and among the fibres of the tissues, he 

 conceives to be, in like manner, centres of assimilation, from obser- 

 ving that they present the same sort of orifice, that they are repro- 

 duced by self- division, and that they are derived from the original 

 cells of development ; that is, from the nuclei of the corpuscles of 

 the blood. He considers that assimilation of the substance intro- 

 duced into the parietal nucleus of the cell is part of the process 

 which propagates the cell ; that the mode of reproduction of cells 

 is essentially fissiparous, and that the process of assimilation pre- 

 pares them for being cleft. 



A pellucid point is described by the author as being " contained 

 in a certain part of the cell-wall, and as representing the situation 



* Dr. Barry requests us to add, that the words " in certain states " are 

 wanted here. — Edit. 



