288. 



SCIENCE. 



[Vol. I., No. 10. 



Cassiopea open, when mature, into the genital sinus, 

 into which Mereikowsky has seen the ripe spermato- 

 zoa escape. He believes that similar openings proba- 

 bly exist in Pelagia; and he thinks the failure of the 

 Hertwig brothers to find them is due to the great 

 complexity of the mature follicle in this genus, rather 

 than to the absence of openings. 



The paper also contains a minute illustrated account 

 of the transformation of the endoderm-cells which 

 line the follicle into spermatozoa. — {Arch. tool. exp. 

 </e(i., 1882, 577.) w. K. B. [616 



Endodermal nervous system in hydroids. — 

 Dr. Lendenfeld states that he independently discov- 

 ered in Australian species of Eudendrium and Cam- 

 panularia the ring of glandular cells which has been 

 recently described by VVeissman and Jickeli in Eu- 

 dendrium. He also finds in all the Campanularidae 

 which he has examined a well-developed nerve-ring 

 of endodermal origin, running around the proboscis, 

 just inside the oral opening. In this region a num- 

 ber of sensory cells aie found, with stiff hairs, which 

 project among the cilia of the endoderm-cells. The 

 study of sections shows that these sensory cells are 

 connected with the ganglion-cells; and the processes 

 which are given off from these ganglion-cells anas- 

 tomose with each other in such a way as to form 

 a complete nerve-ring around the mouth. This ring 

 he regards as the central nervous system of hydroids ; 

 and lie calls attention to the fact that it not only 

 originates from the endoderm, but is without a 

 homologue in the medusae, since none of the medusae 

 are known to have a nerve-ring in this position. — 

 {Zool. anz., Feb. 5.) w. K. B. [617 



Color in Idotea. — Carl Matzdorff has published 

 an elaborate and fully illustrated memoir on tlie color 

 of Idotea tricuspidata (= irrorata), — a variously 

 colored isopod abundant on both sides of the North 

 Atlantic. After describing the various color-vari- 

 eties, which he arranges in five groups, and the 

 minute structure of the integument, particularly the 

 hypodermal pigment-cells, which he regards as true 

 chromatophores, the author discusses at great length 

 the physiology of the changes of color, and the origin 

 of color-varieties. The changes of color are directly 

 influenced, neither by food, temperature, light, nor 

 saltness of the water, but are sympathetic "changes 

 induced by the color of the surrounding objects. 

 Warmtli and light, however, accelerate, and cold and 

 darkness retard, the color-changes. As in other ani- 

 mals, changes in color are produced by contraction 

 and dilatation of different sets of chromatophores. 

 The synonymy of the species is discussed, and a long 

 list of works cited is given; but Dr. Matzdorff, while 

 agreeing with Harger, that the American irrorata 

 and the European tricuspidata are the same species, 

 rejects the earlier name because it has been used only 

 by Americans! — {Jena, zeitschr. naturw., xvi. 1) 

 s. I. s. [618 



The Challenger Amphipoda. — The Rev. T. E. R. 

 Stebbing gives preliminary descriptious of some of 

 the more striking new forms of Amphipoda from the 

 Challenger expedition. Only nine species and one 

 genus are described. Unfortunately, no allusion what- 

 ever is made to the region or depth from which any of 

 the specimens come. — {Ann. marj. nat. hist., March, 

 1883.) s. I. s. [619 



VEETEBEATES. 



The reaction time of olfactory sensations.— 

 The time elapsing between the moment of stimulation 

 and the giving of a signal to indicate the perception 



of a sensation by the person experimented upon, has 

 been measured for auditory, tactile, visual, and gus- 

 tatory sensations. Beaunis has now added to the list 

 by a series of observations made on himself in regard 

 to the reaction time of olfactory sensations. From 

 the table which he gives, it is clear that stimuli, as 

 ammonia and acetic acid, which excite, not merely 

 fibres of the gustatory nerve, but also nerves of com- 

 mon sensation, have a shorter reaction time than 

 stimuli which act only or mainly on the nerve-fibres 

 concerned with the sense of smell proper. Excluding 

 ammonia and acetic acid, the table includes camphor, 

 assafoetida, ammonium sulphide, chloroform, carbon 

 disulphide, valerian, mint, and carbolic acid; and the 

 reaction time increases in the qhove order from ..50 

 to .07 of a second. It was found impossible to deter- 

 mine accurately the moment of olfactory perception 

 of musk. The numbers show that the olfactory re- 

 action time is longer than tactile, visual, or auditory. 

 In a foot-note the author states, that, since writing 

 his paper, he has learned that Buccola of Turin had 

 been, about the same time, at work on the same sub- 

 ject, and had reached results in the main concordant 

 with those above stated. — (Comptes rendus, xovi. 

 387). H. N. M. [620 



Pine structure of bone. — G. Broesike has pub- 

 lished an extensive memoir on this subject {Archiv 

 mikr. anat, xxi. 695), of which Eberth has published 

 an abstract, here reproduced. The first part of the 

 paper deals with the limiting-sheaths of the osseous 

 canal system. The sheaths may be isolated by the 

 action of acids on completely macerated bones. They 

 are but slightly pliable, and reproduce perfectly the 

 forms of the canals. They may be destroyed by cer- 

 tain reagents quicker than the basal substance of 

 bone, from which they are therefore different, their 

 substance resembling keratine in the author's opinion. 

 The slieaths are wanting in embryonic and all young 

 bone. The author speculates as to their origiu : he 

 thinks they must arise either as a precipitate from the 

 lymphatic fluids, or else by decalcification of the basal 

 substance. (Neither of these views appears probable. ) 

 The osseous corpuscles form a continuous network 

 by tlie union of their processes. These cells probably 

 have no membrane, and the nucleus soon degenerates. 

 With increasing age, the cells loose their process, and 

 become jagged and smaller, so that there is a space 

 around them; then follows fatty metamorphosis of 

 the protoplasm, and finally complete fatty degenera- 

 tion, of whicli the products may be resorbed. The 

 author advances the (very improbable) hypothesis, 

 that the corpuscles are killed by smothering in car- 

 bonic acid, accumulated in parts of the bone remote 

 from the blood-vessels. The basal substance consists 

 of uncalcified gelatine, yielding fibrillae, embedded in 

 a calcified cement. The lamellae are formed by 

 primitive layers of fibrillae, which do not intercross 

 and intertwine, although the sets of parallel fibrillae 

 run in various directions. The author distinguishes 

 between regular and irregular fibrillar tissue. — 

 {Fortschr. med.,\.lQ.) c. s. M. [621 



Nerves of the small blood-vessels. — L. Bremer 

 gives a brief resumi of previous opinions on this sub- 

 ject, and reports his own observations made prin- 

 cipally on frogs and lizards. He asserts that his 

 statements also apply to the warm-blooded vertebrates. 

 The fine capillaries are accompanied by usually two 

 naked nerve-fibres, which anastomose with one an- 

 other, and give off fine branches which form a plexus 

 around the vessel. The threads of the plexus give 

 off fine knot-like thickenings on the side towards the 

 wall of the vessel, and these knots are the ultimate 

 terminations. On the veins and arteries there are 



