HA RD WICKE'S SCIENCE- G OS SIP. 



i ii 



friends are a deal too active for our purpose, rushing 

 about the live cell in a manner that precludes all 

 continuous observation. Under these circumstances 

 an excellent dodge is to add, with a pipette, a very 

 minute quantity of alcohol to the water in the cell. 

 After a few vigorous kicks the creature becomes 

 stupefied, and only moves in the sluggish manner 

 best suited for our purpose. The effect of the dose, 

 however, soon wears off, and a little more will 

 usually require to be added from time to time, when- 

 ever the movements become undesirably extensive. 



In such transparent creatures the process of death 

 is most curious and instructive to witness, more 

 especially in small crustaceans, such as Leucifer, 

 Saphirina, immature Squillse, etc. 



Almost as soon as the last movements cease, the 

 nervous centres commence to become granular, rapidly 

 followed by the connecting commissures and peri- 

 pheral nerves. This takes place some time before 

 the other structures at all lose their transparency ; 

 and it is often ' possible to make a camera lucida 

 drawing of the entire nervous system, in all its rami- 

 fications, before the supervention of muscular opacity 

 obliterates the picture. No dissection could possibly 

 rival the exactness of the results obtainable in this 

 way, were even the animals of sufficient size to make 

 such a process practicable. Next after the nerve 

 elements, the muscles become opaque ; and during 

 the process much may be learnt as to the anatomy of 

 the limbs as well, in flat things like Saphirina, of the 

 body muscles, during the process. 



Finally, the fluids of the general body cavity coagu- 

 late, their cellular elements become opaque, and the 

 process of tissue death is complete. It is difficult to 

 give any adequate idea of the wonders that may be 

 followed in the living and dying animal. No object, 

 e.g., could be better suited for the study of living 

 muscular fibre than the limbs of some of these minute 

 crustaceans, which are often thin enough to admit of 

 examination with powers as light as I-I2. 



I have occasionally succeeded in, to some extent, 

 preserving this dissected appearance of the nervous 

 system, by staining with borax carmine, and subse- 

 quent treatment with dilute acid in the usual way. 

 The specimens in which this occurred were placed 

 in the stain in the living state, or nearly so ; and, as 

 the result was by no means uniformly obtainable, 

 I am inclined to believe that the secret of success 

 lies in completing the process before the muscle 

 fluids have had time to coagulate thoroughly. This, 

 however, is but speculation, and further experiments 

 are required to establish the conditions essential to 

 success. 



If it is desired to keep any single specimen under 

 observation alive for any length of time, it is abso- 

 lutely necessary to keep the water of the live cell 

 thoroughly aerated ; and a little apparatus for the 

 purpose can be very easily and cheaply constructed 

 as below. 



Procure a couple of tin bottles, such as are used by 

 workmen for carrying their tea to work with them. 

 Have soldered into the side of each, close to the 

 bottom, a piece of small brass tubing, about an inch 

 in length. It is essential that the necks of the tins 

 should be of the same size, so that the same cork 

 may fit both. Into this cork fit a short piece of glass 

 tubing, bent twice at right angles. A small brass 

 tap, such as is supplied with injecting syringes, is 

 connected with this tube by means of a short length 

 of indiarubber piping, and about a yard of narrow 

 rubber tubing is fitted on to the nozzle of the tap ; 

 the other end being slipped on to a piece of small 

 glass tube, about three inches long, having its end 

 drawn out to a fine point, and bent at right angles 

 about half an inch from it. The brass pipes at the 

 bottom of the tins are now connected by about one 

 yard and a-half of rubber tubing, and the apparatus 

 is ready for use. 



To set it to work, insert the cork, with its tap 

 closed, into one of the tins, and fill the other with 

 water. Now raise the full tin to a couple of feet 

 above the level of the other, place the fine point of 

 the tube in the live cell, and gently turn on the tap. 

 The point should be kept as far away as possible 

 from the specimen, as, if too near, the stream of 

 bubbles will give it a vibratory motion fatal to obser- 

 vation. The tap should be so turned that the stream 

 of air may be very gentle, just allowing one small 

 bubble to follow the next. Under these circumstances 

 the stream of air will last fifteen or twenty minutes. 

 When the upper tin has become empty, all that is 

 necessary is to shift the cork into it, and reverse the 

 places of the tins. Fig. 54 shows the tube arranged 

 in the live cell, and Fig. 55 the general arrangement 

 of the apparatus. 



{To be continued.) 



CARNELIAN ARROW-POINTS FROM 

 ARABIA. 



I HAVE lately obtained what I believe to be some 

 specimens of great interest to the student of pre- 

 historic archaeology, namely some small arrow-points 

 of carnelian and jasper from Arabia. These objects 

 were loosely strung in the form of a rude necklet, 

 for which purpose they were bored through their 

 smallest diameter, and near the broad part of the 

 arrow- point. 



At first sight I was of the opinion, that they were 

 crudely fashioned in this shape as a mere fancy by 

 the persons who had bored and strung them ; but I 

 observed that the boring was sharp and rough, 

 rendering the surface of the boring opaque. 



The outline, however, of the arrow-tips themselves 

 was not so, but, on the contrary, was highly polished 

 and decidedly sub-angular, notwithstanding that the 

 flaking and trimming were distinctly traceable. In 



