July 23, 1896J 



NA rURE 



287 



and is about as large as the nucleolus of the latter. It rapidly 

 spreads over a part of the female nucleus as a cap, and it presents 

 a less homogeneous aspect than before. Both it and the female 

 nucleus assume a granular character, which is probably to be 

 interpreted as representing a coiling and looping of the linin of 

 the respective nuclei. Finally the two nuclei coalesce, and the 

 original components can no longer be distinguished. Complete 

 fusion may be eft'ected in less than ten minutes after the addition 

 of the antherozoids to the water. 



A delicate pellicle is meanwhile formed around the periphery 

 of the oosphere, which is thus easily distinguished from the 

 unfertilised oospheres, in which such a membrane is wanting. 

 The texture of the cytoplasm also changes, and tends to assume 

 a more definitely radiating character, the lines starting from the 

 nucleus .is a centre. 



After fertilisation, the cells rest for a long interval of time — 

 commonly about twenty-four hours — liefore they begin to 

 segment. The principal changes which occur during the 

 interval are, first, in the rapid increase in the thickness of the 

 j-ieripheral cell wall, and, secondly, in the more regular arrange- 

 ment of structure exhibited by the protoplasm. The alveolar or 

 foam character is extremely clear, and the chromatophores, 

 which by this time have become very prominent, are noticed to 

 be situated in the angles formed by the convergence of the foam 

 walls ; they are often bent and otherwise distorted, and so 

 accommodate themselves to the structural condition of 

 the foam. 



The first segmentation-division resembles, in a general way, 

 the oogonial nuclear divisions already described. The achro- 

 matic fibrils forming the polar radiations are clearly seen to be 

 attached to the foam-like structure of the cytoplasm, and, in 

 some cases, insensibly to pass into it. At other times fibrils 

 end on granules (or, perhaps, on the protoplasmic lining of the 

 granules), and sometimes again a fibril may fork, and its 

 branches end either on granules or on the foam angles. The 

 interpolar portion of the spindle is intranuclear, and the 

 chromosomes, when arrayed at its equator, are seen to be hvice 

 as niimcrotis as those in the oogonial spindles. This doubled 

 number is maintained throughout the thallus divisions, and the 

 reduction in their number only occurs in connection with the 

 actual differentiation of the sexual cells. The theoretical 

 conclusions to be drawn from these facts were briefly indicated 

 by the authors. 



" Phenomena resulting from Interruption of Afferent and 

 Efferent Tracts of the Cerebellum." By Dr. J. S. Risien 

 Russell, Research Scholar to the British Medical Association. 



Continuing his researches into the functions of the cerebellum, 

 the author has directed his attention to the effects of dividing 

 one inferior peduncle of this organ. He finds that in the 

 disorders of equilibration which result, the direction of rotation 

 is towards the side of the lesion, or, in other words, if, as was 

 always the case, the left peduncle was divided, the animal 

 rotated like a right-handed screw entering an object. 



The disorders of motility which result from such a lesion 

 correspond exactly with those observed after ablation of one 

 lateral half of the organ, and consist in defective movement in 

 the limbs on the side of the divided peduncle, and of the 

 posterior limb of the opposite side. It is suggested that these 

 effects may result from the interruption of afferent impulses 

 passing to the cerebellum, rather than from the cutting off of 

 etTerent impulses from the cerebellum to the spinal centres. 

 The interruption of similar impulses are held responsible for the 

 displacement of both eyes downwards and to the opposite, a 

 displacernent which also resulted after removal of one lateral 

 half of the cerebellum. 



Spasm, which was easily detected in the back and neck 

 muscles on the side of the lesion, causing incurvation of the 

 vertebral axis to that side, alone furnished any satisfactory 

 information in support of the view that the cerebellum exerts an 

 inhibiting influence on the spinal centres ; but the tendon reflexes 

 afforded no satisfactory information on this point. 



Sensibility was blunted on those extremities in which motor 

 power was defective, a point in favour of the author's previous 

 contention that the cerebellum is concerned with sensory as well 

 as witli motor processes. 



The excitability of the cortex of the opposite cerebral hemi- 

 sphere to the I'aradic current was less than that of the hemisphere 

 on the same side as the divided peduncle, a result which 

 strengthens the view that' one lateral half of the cerebellum 



exerts a control on the opposite cerebral cortex, as was suggested 

 by certain results previously obtained by the author, and which 

 further points to the possibility that the cerebelluin is in its turn 

 inhibited by afferent influences which reach it from lower 

 centres. This view is made still more proimble by the remark- 

 able results obtained by the intravenous injection of absinthe 

 after division of one inferior peduncle of the cerebellum, for 

 during the otherwise general convulsions which resulted, there 

 was a complete absence of convulsions in the muscles of the 

 anterior extremity on the side of the lesion, and a diminution 

 of the convulsions in the muscles of the posterior extremity of 

 the same side. 



These results were supplemented and controlled by other 

 experiments in which the lateral tracts of the medulla oblongata 

 were divided on one side without injury to the pyramid, by 

 others in which the posterior columns and their nuclei were 

 divided on one side, and by others in which partial hemisection 

 of the medulla was performed, including all the structures on 

 one side with the exception of the pyramid. 



Paris. 

 Academy of Sciences, July 13. — M. A. Chatin in the 

 chair. — On the flow of liquids in large rectangular channels, and 

 in pipes or canals of circular or semicircular section, by M. J. 

 Boussinesq. — On the law of corresponding states of Van der 

 Waals, and the determination of the critical constants, by 

 M. E. H. Amagat. Some applications of the method of pro- 

 jection described in a previous note. Taking the critical con- 

 stants of any one substance, the determination of which may be 

 looked upon as the most trustworthy, the critical constants of any 

 other substance may be determined in terms of these from the 

 experimental pi' curve. — On a new method for the determination 

 of the respective distances of the centres of cerebral localisation, 

 by M. C. Henry. — Remarks, by M. Langlois, on a new theory 

 of capillarity. — On the fixing of photographs in colour on paper, 

 by M. A. Graby. — Aerial navigation, by M. L. Gardere. — On 

 differential equations of the first order, by M. P. Painleve. A 

 reply to a note of M. Korkine. — On groups of substitutions, 

 by M. G. A. Miller.— On the function C(s), by M. Hadamard. 

 Pointing out that a part of a proof given in a preceding note is 

 not rigorously true. — On the displacement of the axis of rotation 

 of a solid body of which a part is rendered instantaneously 

 mobile with respect to the rest of the mass, by MM. Edmond 

 and Maurice Fouche. — On the elastic equilibrium of a revolving 

 body, by M. L. Lecornu. — On a graphical representation of 

 luminous waves, by.M. G. Vert. — On the verification of the 

 theorem of corresponding states, by M. C. Raveau. By taking 

 the logarithms of pv and / as co-ordinates, instead of pv and /, 

 the method suggested by M. Amagat is much simplified in 

 its application. — On an absolutely astatic galvanometer of high 

 sensibility, by M. A. Broca. — On the vaporisation of metals at 

 the ordinary temperature, by M. II. Pellat. Results similar to 

 those obtained by M. Colson with zinc are obtainable with steel. 

 In view of the experiments of M. Becquerel \yith metallic 

 uranium, it is suggested that similar invisible radiations, and not 

 the vapour of the metal, may produce the efiects observed. — 

 Method for photographing in reverse, objects in relief, by M. E. 

 Moussard. — On the manner in which the X-rays cause the dis- 

 charge of electrified bodies, by M. Emile Villari. Some ex- 

 periments tending to show that the discharge is due to convection 

 currents in the air surrounding the charged body. — The action 

 of tubes and metallic discs upon the X-rays, by the same. — The 

 action of the Rontgen rays on the diphtheric bacillus, by M. F. 

 Berton. No attenuation of the virus could be obtained by ex- 

 posure to the rays for forty-eight hours. — On the fusibility of 

 metallic alloys, by M. Henri Gautier. A study of the fusibility 

 curves allows of the prediction of the existence of the following 

 alloys of definite composition : NigSuj, SnAI, AgjAI, and 

 SbAl, the last of which was isolated by C. Alder Wright.— 

 Diamonds in steel, by M. Rossel. — Action of silicon upon cer- 

 tain metals, by M. E. Vigouroux. The alkali metals, zinc, 

 aluminium, lead, tin, antimony, bismuth, gold and silver dis- 

 solve silicon more or less, but do not combine with it directly. 

 Iron, chromium, nickel, cobalt, manganese, copper and platinum, 

 on the other hand, form definite silicides. — Researches on the 

 double cyanides, by M. R. Varet. —Action of water upon formic 

 aldehyde, by M. Marcel Delepine. Formic aldehyde with water 

 at 200' gives CO, COj, formic acid and methyl alcohol. — Reduc- 

 tion of crotonic aldehyde, by M. E. Charon. By the use of the 



NO. 1395, VOL. 54] 



