392 Notes and Memoranda. 



of mercury, and other salts of that metal, had the property of preventing the 

 coloration of starch hy iodine, which, however, appeared on addition of chloride 

 of sodium, sulphate of potash, hydrochloric, hydrobromic, or hydriodic acids. 



The Poraminifera oe the Alps. — At the same meeting, Professor Kauff- 

 mann stated that the foraminifera which were so abundant in the cretaceous rocks 

 of the Alps, resembled those of the same formation in other countries. In order 

 to see them well, it was necessary to polish the stone, heat it to a dark red with a 

 blow-pipe, gently rub the surface with oil, and view with strong magnification. 

 The effect of heating was to bring out the lines of the shells in contrast with the 

 stone. When the shells were separated from the chalk, he mounted them in 

 Balsam of Tolu, which does not harden, in preference to Canada Balsam. 



Development of Tubtjlaria. — At the same gathering, Professor Claparede 

 gave a sketch of the development of hydroida belonging to the genus tubularia. 

 On emerging from the egg the embryos resembled the simplest of the naked-eyed 

 medusse, although their digestive cavity was a simple sac, which did not give rise 

 to gastric canals. They floated passively on the surface of the water, without the 

 movements of contraction and expansion that characterized true medusa. Prom 

 the midst of a crown of tentacles sprung a manubrium (literally handle), as in the 

 medusa?. This organ exhibited at its extremity a small opening which, by analogy, 

 must be considered as a mouth. After the lapse of some days, the top of the 

 umbrella elongated, and from its surface arose five little eminences surrounding a 

 depression which grew deeper and deeper, and at last constituted a true opening, 

 communicating between the digestive cavity and the external world. This was 

 the true mouth, and the little eminences were the tentacles in an incipient state. 

 At this time the little embryo fixed itself to some body by its manubrium, and gave 

 up its wandering life. The manubrium elongated and constituted, the peduncle of 

 the young tubularia. The primitive tentacles, which at first were directed down- 

 wards, as with the medusae, reversed their position, pointed upwards, and formed 

 the crown of the tubularia. 



Formation of Eapkides. — Dr. Beinsch, of Basle, laid before the same body 

 his observations on the well-known crystalline deposits or raphides in the tissues 

 of vegetables, and especially on those of the root of the Convallaria multiflora. 

 He found that when he dissolved, by means of a re-agent, the crystals contained 

 in a cell, there remained a membrane of exactly the same form. This membrane 

 is coloured an intense yellow by iodine, and appears to have the same constitution 

 as the primordial vesicle. 



Velocity of Nerve Porce. — M. Hirsch exhibited to the same Society an 

 apparatus for determining what astronomers call the personal equation of time, or 

 the difference which observers make from personal causes in the estimation of 

 minute periods. He said, " We have now introduced the electric method into 

 astronomical observation, and as the observer has only to shut off the current as 

 soon as he sees the bisection of a star, the problem of personal equation consists 

 in determining the time which is necessary for the astronomer to see and execute 

 the necessary movement of his finger. This time, which we call physiological 

 time, consists of three elements : 1. The time occupied in transmitting the im- 

 pression to the brain. 2. The time taken by the brain to transform the sensation 

 into a volition, and 3, that consumed in transmitting this volition through the 

 nerves, and in the execution of the muscular movement." To ascertain these 

 minute periods, M. Hirsch employs the Chronoscope of M. Hipp. A ball is so 

 arranged that its fall interrupts an electric current, and thus sets free the motion of 

 certain hands. As soon as an observer perceives the fall of the ball, he remakes 

 the contact, and arrests the hands, whose motion in the interval gives the physio- 

 logical time. By the use of this instrument M. Hirsch has come to the conclusion 

 that nerves transmit their impressions at the rate of thirty-four metres a second. 

 Mr. Heimholz estimated their velocity at 190 feet per second, but his experiments 

 were on the motor nerves of frogs, and those of M. Hirsch on the sensitive 

 nerves of man. We have condensed the four preceding paragraphs and this, from 

 the Archives des Sciences, and, with reference to the experiments of M. Hirsch, we 

 should imagine the rate at which nervous impressions travel would probably vary 

 in different individuals, and in the same individual at different times. 



