SCIENCE-GOSSIP. 



127 



A STUDENTS' MICROSCOPE. 



\ T TR illustrate a useful instrument manufactured 

 v v by Carl Zeiss, especially suited to natura- 

 lists on account of its portability. When packed 

 in its box the instrument only occupies 12 inches x 

 7i X 65 inches. The case contains fittings, sliding 

 boxes for tubes, slides, etc., also sliding blocks for 

 cover-glasses and objectives, with other blocks for re- 

 agents. The price of the stand is £6, and objective 



Carl Zeiss Students' Microscope. 

 Stand VIa. 



styled " A," costs 24s., and " D," 425. each. They 

 are equal to f-inch and J-inch, or the ordinary 

 student's objectives. These stands are very solid 

 and steady, so that no student need wish for a 

 better working instrument than the one now sub- 

 mitted for our examination. 



THE FOREST OF FRANKFORT. 



T7RANKFORT has its forest as London has 

 Epping Forest. The one at Frankfort is a 

 little larger than Epping, being roughly 8,000 acres 

 against 6,000 acres. Like Epping it is under the 

 management of the City, but is close at hand being 

 only separated by the river Main. The trees are 

 naturally mainly beech and oak, but early in the 

 fifteenth century, conifers, chiefly Scotch pine 

 were introduced, and now the woodlands present a 

 very varied appearance of mixed species of trees. In 

 extent it reaches about eight miles long by three 

 miles broad, being divided into two circles, 

 Oberwald and Unterwald. In the former beech 

 predominates on the limestone soil. It is needless 

 to add that the naturalists have at their doors a 

 beautiful observation and collecting ground. 



THE EVOLUTION OF THE EYE. 



/^ATTAIN Abney has been making ,ume rather 

 remarkable observations on the development of 

 the eye, and it may perhaps interest readers of 

 Science-Gossip to hear some of his opinions on 

 the subject. The evolution which the eye has 

 undergone may be expressed as follows: (1) the 

 appreciation of light ; (2) black and white ; (3 1 

 form ; (4) colour. 



Captain Abney gives examples to illustrate his 

 theory. The Area, for instance, is a mollusc 

 which has no palpable head and yet it possesses 

 an organ which enables it to distinguish between 

 light and darkness. The limpet has an eye which 

 is rather more advanced in development, and the 

 next stage is a depression which acts as a retina. 

 Then we may take the eye of a snad which has 

 an orifice covered with a transparent membrane. 

 Then we come to the eyes of the higher 

 cephalopods which can distinguish black and white, 

 and form, but not colour. Lastly we have the 

 human eye with its appreciation of light, 

 chiaro-oscuro, and colour. Captain Abney thinks 

 there is little doubt that the first colour-receiving 

 apparatus which was evolved was that which 

 enabled the eye to appreciate blue, next came green, 

 and finally red. A full report of Captain Abney's 

 paper will be found in the " Journal of Camera Club" 

 for February. While on the subject of the eye it 

 may be interesting to refer to the artificial spectrum 

 top, recently brought out by Newton's, of Fleet 

 Street. A card containing black and white bands 

 are rotated and distinct colour-bands are seen. It 

 is of interest to note that this discovery was 

 anticipated by Mr. S. N. Stewart, of Manchester. 

 In the Proc. Roy. Soc. Edin., xv., he states that 

 he found certain colour-phenomena were caused 

 by intermittent stimulation with white light. 



M. Hugo Magnus, Professor of Ophthalmology 

 at Breslau, in Germany, in a recent paper on the 

 " Sense of Colour in Man," appears to think that 

 man's organ of vision will become more and more 

 perfect as he accustoms himself to analyze his 

 sensations, and that in the future the human retina 

 will be capable of seeing colours which, at the 

 present time, do not act upon it at all. Primitive 

 man, according to M. Magnus, at first saw no 

 colours : he could but distinguish light, shade and 

 form. Then, as he grew more civilized, he saw 

 red and yellow. This can be proved, says our 

 author, for "neither in the ancient hymns of the 

 Vedas nor in the Old Testament is there mention of 

 a blue sky, and neither Homer nor Ezekiel appear 

 to have been sensible of nearly all the tints of the 

 rainbow." The truth seems to be, that the ancients 

 saw as many colours as we do to-day, only they 

 had not words to describe all they saw. 

 • Kensington. Herbert C. Fyke. 



