278 Miscellaneous. 



The ovum, examined two or three hours after deposition, consists 

 of a network of granular protoplasm, in the meshes of which are 

 contained the spheres of the deutoplasm. The surface of the ovum 

 is covered by a continuous layer of protoplasm, a layer the exist- 

 ence of which Ludwig has erroneously denied, and which he has 

 confounded with the chorion covered with projecting granules. 

 This layer divides very clearly into germinative areas, as was first 

 described by Balbiani : and, notwithstanding the contrary asser- 

 tions of Ludwig and Barrels, I have been able to grasp the mode 

 of formation of this division, and to ascertain that it has a signifi- 

 cance different from that ascribed to it by Balbiani. It is due to 

 the transference of the protoplasm from the interior to the surface 

 of the ovum. Hyaline protoplasm gushes forth in the intervals of 

 the vitelline spheres of the surface, and divides the granular layer. 

 This phenomenon has no particular influence upon the formation of 

 the blastodermic cells. It is the result of a centrifugal tendency of 

 the protoplasm, which governs the first phases of development in the 

 Araneida. 



A few hours after this division there appear at the surface of the 

 ovum at first large, diffused, deep spots, and soon afterwards dark 

 stellate figures, described by Balbiani, and surrounded by the bril- 

 liant rosettes of Ludwig. The dark stellate forms are true salient 

 disks of granular protoplasm, having a large pale nucleus in their 

 centre. Sections made at this moment show that the disks issue from 

 trains or dissepiments of the same nature, which separate and englobe 

 the neighbouring vitelline spheres. 



In ova taken before the formation of the rosettes of the surface I 

 have never ascertained the existence of the cylinders of deutoplasm, 

 or '■'■ DeutopJasmasaulen " of Ludwig, in the interior of the ovum 

 itself ; and I do not think that we can adopt the opinions of that 

 author as to the mode of segmentation of the ovum by the succes- 

 sive splitting of the central rosettes. What is really the case is that 

 the protoplasm grouped around the nuclei moves from the interior 

 towards the surface, drawing more and more towards it the proto- 

 plasm of the dissepiments, and producing first of all diffused spots, 

 which become resolved into dark superficial rosettes. 



From the examination of sections it appears : — 1. That the granu- 

 lar protoplasm, at first diffused pretty uniformly in the form of a 

 network between the spheres of deutoplasm, bears more and more 

 towards the periphery of the ovum, at the same time concentrating 

 around a small number of nuclei. 2. That the masses of proto- 

 plasm appear at the surface in the form of dark lenticular masses or 

 disks, from which issue rays of the same substance, which separate 

 the surrounding vitelline spheres and envelop them in the form of 

 partitions. It is to the thickness of the interposed dark septa, and 

 very probably also to the centripetal contraction of these septa, that 

 these vitellne spheres owe the very strongly -marked appearance of 

 their contours and the elongation of their axis towards the centre of 

 the dark disk, conditions which produce the phenomenon of the 

 brilliant rosettes of Ludwig. But these rosettes can only exist at 



