April io, 1902] 



NA TURE 



535 



It is now some three or four years since I discovered fibrils, 

 hovering upon the limits of vision aided by the best oil-immer- 

 sion lenses, which ran from nucleus to nucleus in the retina of 

 vertebrates. The first hints were slowly followed up, and I have 

 flow established the fact that all the nuclei of the retina are 

 connected to[;ether, l>y fibrils coming from the intra-nuclear 

 networks, into a nuclear system ; that is, into a reticulum of 

 which the individual nuclei are the nodes. 



As a student of the retina, my first interest in this nuclear 

 system pervading the cytoplasmic framework turned upon the 

 fact that it might supply us with the hitherto undiscovered 

 link between the retinal nerve strands and the rods. This I 

 have found to be the fact ; the full details are described in a 

 paper which I hope shortly to publish. 



The importance of this discovery cannot, however, be confined 

 to the retina. Xot only have I succeeded in discovering similar 

 inter-nuclear connecting fibrils in other tissues, e.g. in the 

 brain, but the simple fact that in the retina they supply the 

 paths for the nerve stimuli shows that they must lie somewhere 

 nearer the basis of the morphology and physiology of proto- 

 plasm than we have hitherto succeeded in reaching. 



In discussing the nature of this nuclear network and its bearing 

 upon the " cell " doctrine, I have described a number of obser- 

 vations tending to show its relations, on the one hand, to the 

 chromatin stored up in the nuclei, and, on the other, to the 

 cytoplasm which forms the supporting framework of the retina. 

 I have, further, endeavoured to show that it brings fresh light 

 upon more than one difficult problem, for example, on the 

 morphology of nerves and the nature of their peripheral 

 terminations. 



Several lines of argument made it almost certain to my mind 

 that a similar nuclear network must also exist in plants, and I 

 have little doubt but that Prof. Macfarlane's suggested con- 

 tinuity of the " hereditary substance " from " cell" to "cell" 

 will ere long be demonstrable under the microscope. 



I have suggested the term protomitomic as applicable to this 

 nuclear system, that being as nearly as possible simply descrip- 

 tive. The nuclear filaments, it is true, seem to supply some of 

 the requirements of Strasburger's hypothetical kinoplastic 

 fibrillar system. But the term kinoplasm, which I should have 

 preferred using, has already passed into current use for struc- 

 tures which may have little or nothing to do with this nuclear 

 connecting system, a preliminary announcement of which I have 

 felt justified in making since my attention was called to Prof. 

 Macfarlane"s address. Henry M. Bernard. 



Clapham, S.W.. March 25. 



Beechen Hedges on Elevated Ground. 



Visitors to Buxton, who are observant of trees, have been 

 exercised during the winter by noticing how the smaller beech 

 trees, where isolated, and especially the beechen hedges, where 

 unsheltered, have maintained their foliage through the winter, 

 contrary to the habit of deciduous trees. 



The spray enclosed was plucked, this morning, from a tree 

 about 12 ft. high, one of a number similarly clothed, bounding 

 the western side of the pavilion grounds where exposed to the 

 force of the storm winds, and standing at the elevation of the 

 town, about a thousand feet above the sea : and, in the park 

 close at hand, are long lengths of beech hedges exhibiting this 

 appearance. In Ashwood Dale, half a mile away and well 

 sheltered, the larger beeches are as leafless as the lime and the 

 ' ash. 



I see nothing in Kerner's " Natural History of Plants " to 

 account for this departure — this tree being spoken of as con- 

 stant in dropping its leaves — except the remark that the beech 

 is most resourceful and to be regarded as a " weed " amongst 

 trees, and calculated to oust others, where unhindered by 

 human agency. Is this holding of the leaves, until pushed off 

 by the growing points, to be regarded as a protective device 

 in exceptional circumstances, and is this occurrence ob- 

 servable in young plants in similar elevated and exposed 

 positions? Wm. Gee. 



Barlboro' Cottage, Spring Gardens, Buxton, March 31. 



Meristic Variation in Trochus Zizyphinus. 

 On recently examining a number of specimens of Troihu! 

 zizyphinus collected at Plymouth in September 1900, it was 

 noticed that one specimen exhibited a peculiar abnormality, viz. 



NO. 1693. VOL. 65] 



the presence of two supernumerary eyes on the right side (Fig. i ). 

 On the left side of the animal both cephalic tentacle and ocular 

 peduncle were perfectly normal. The right cephalic tentacle 

 was also normal, and the ocular peduncle of this side, though 

 bearing three eyes, presented only a slight furrow indicating a 

 partial division between the original eye and the two which are 

 secondary and supernumerary (Fig. 2). Several cases of super- 

 numerary eyes in Gasteropods have already been recorded, and 

 in some cases (for example, Patella, Litloriud) duplication of the 

 eye is accompanied by duplication of the cephalic tentacle. 



— - Ocular peduncle. 



Cephalic tentacle 



[. — Head of abnormal specimen of Trochus zizyphinu 

 right side. 



Double eyes have also been recorded in Heli.x, Claiisilia, 

 Phidiana, Murex, and Sub-emargimila'^ ; in the latter, super- 

 numerary eyes were found on both right and left sides, though in 

 the majority of other cases they were present on one side only. 

 It would thus appear that only double eyes have been so far 

 recorded, and that the presence of three eyes on the right side 

 of this abnormal specimen of Trochus is, apparently, unique. 

 All three eyes are perfectly formed, each being provided with 

 crystalline lens, retina, and optic nerve, thus all of them were, 

 in all probability, functional during life. 



;. — Longitudinal secti 



n of right ocular peduncle, ; 

 eyes in section. 



So far as can be made out from the examination of an un- 

 fortunately incomplete series of longitudinal sections through 

 the right ocular peduncle, the innervation of the eyes is derived 

 from a single optic nerve arising from the right cerebral ganglion. 

 This nerve bifurcates, one branch going to the primary eye, the 

 other branch again dividing into two, to supply the two secondary 

 supernumerary eyes. W. B. Randles. 



Royal College of Science, London, March 25. 



' For particulars and 

 of Variation," pp. 279, 2 



efer. 



: Bateson's " Materials for the Stud^- 



