ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 559 



Acalephs, Polyps, Ehizopods have not a considerable range, and may 

 pass either vertically or near the bottom through layers of water of very 

 considerable differences of temperature and pressure. 



It is to be borne in mind that nearly all the Eadiolaria which Dr. 

 Chun took with a tow-net at a depth of 300 fathoms have also been 

 collected at the surface, and the same is true of some other forms. The 

 author seems to have demonstrated for surface pelagic animals a far 

 greater bathymetrical range than they were known to have, and one 

 which, perhaps, corresponds to the wide bathymetrical range of many 

 so-called deep-sea types, which extend from the greatest depths at which 

 animals have been dredged almost to the regions of the littoral belt. 



Dr. Chun gives an account of the development of Ctenophora, and 

 shows that the Cydippe-iovra of Bolina, after the degeneration of the 

 genital organs, which are fully developed soon after leaving the egg- 

 envelope, is developed into the BoUna-iovm. ; this peculiar mode of 

 reproduction he calls Dissogonie. 



Physiology of Nervous System.* — Herr Steiner has made some 

 experiments on nervous functions among Invertebrates. The cerebral 

 ganglion of the crayfish is shown to be the general locomotor centre. 

 In the leech, however, this is not the case ; the removal of the cerebral 

 ganglia made no great difference ; even separated portions crept about. 

 In Pterotrachea mutica, a conveniently transparent mollusc, the removal 

 of the central ganglion made no difference, but movement ceased with 

 the destruction of the pedal. The latter is the general and the only 

 locomotor centre of the body. One side of the pedal ganglion was 

 removed in the pelagic CymhuUa, which then exhibited circular move- 

 ments on the injured side. Eemoval of the cerebral ganglion in Octopus 

 vulgaris stopped voluntary and spontaneous nutrition, but the reflex 

 action of the eye persisted. The removal on one side of the anterior 

 portions of the sub-oesophageal ganglion led to circular movements as in 

 Gymhulia. In Appendicularia the tail ganglion is the locomotor centre. 



MoUusca. 

 a. Cephalopoda. 



Shell-growth in Cephalopoda. — Professor J. F. Blake f urges that 

 Mr. F. A. Bather, whose communication has been already noticed, J has 

 added nothing of value to what he himself taught as to the morphology of 

 the shell in the Introduction to his work on ' British Fossil Cephalopods.' 

 Mr. F. A. Bather § replies that Prof, Blake now appears to accept the 

 view which it was his object to defend rather than originate — namely, 

 that successive chitinous membranes are given off by the body-surface 

 and subsequently calcified, but that that is not the teaching of the Pro- 

 fessor's monograph. Prof. Blake criticizes the suggestion that the 

 membranes of the septa are typically continuous with those of the shell- 

 wall, but it is urged that not only are the two descriptions that he gives 

 inconsistent with one another, but both are in disagreement with the 

 facts of the case. Objection was also taken to the assumption that 

 the lamellae of Sepia are homologous with the septa of a Belemnite- 

 phragmocone, but this is an old view first taught by Voltz in 1830, held 

 by many first-rate observers, and supported by original observations on 

 Mr. Bather's part. 



* Biol. OentralbL, vii. (1888) pp. 732-3 (60 Versamml. Deutsch. Naturf. Wies- 

 baden, 1887). t Ann, and Mag. Nat. Hist., i. (1888) pp. 376-80. 

 J Ante, p. 397. § Tom. cit., i. (1888) pp. 421-7. 



