230 



♦ KNOWLEDGE ♦ 



[Sept. 19, 1884. 



Humain," from which the previous case is cited, there is 

 a plate representing the right cerebrum entirely destroyed 

 by apoplexy ; yet the owner of this half-destroyed brain, 

 "jouissait de toute son intelligence." 



It is singular that Cruveilhier, in dealing with this and 

 similar cases, speaks of the intelligence remaining unim- 

 paired, with so little emphasis as to show that he had not 

 paid special attention to the circumstance. Yet surely 

 nothing can be more thoroughly inconsistent with the belief 

 that the biain is to be regarded as a single organ, in this 

 sense, at least, that the various portions of it are all essen- 

 tial to its complete action. 



The same is the case with other writers, — as for instance 

 with Dr. Abercrombie, who dt-scribes a case in which there 

 was a frightful cavern in the right side of a man's brain, 

 yet the man preserved bis intelligence entire until the very 

 moment of his death, — without dwelling in the slightest 

 degree on the conclusion to which such a case seems inevi- 

 tably to point. 



(To be continued.) 



AN AERIAL PROPELLER. 



THE accompanying engraving represents an aerial pro- 

 peller recently j)atented by Mr. M. H. Depue, of 

 Homer, 111. The propeller. Fig. 2, has a rim and hub in 



which are jourrialed radial blades ; each journal of each 

 blide being provided with two transverse arms in the same 

 ■plane. The main rudder for guiding and controlling the 

 machine is shown in the right side of the perspective view. 

 Upon each side, at the other end of the balloon, is a rimular 

 rudder used to raise and lower the machine when balanced 

 in the air, thereby avoiding the necessity of throwing out 

 ballast or letting out gas. The under part of the balloon, 

 next to the car, is made straight, tliereby giving the pro- 

 peller more power, and the car a better sha])e for the other 

 attachments. When the car descends, it alights upon 



small wheels, which prevent scraping and sliding on the 

 ground. Figs. 3 and 4 show the hub of the wheel and the 

 frame and a single paddle or blade in different positions. — 

 Scientific American. 



PLEASANT HOURS WITH THE 

 MICROSCOPE. 



By Henry J. Slack, F.G.S., F.R.M.S. 



THOSE who live near heaths should at least examine 

 the three most common sorts, if they are in a 

 region that does not grow the rarer kinds. Ling, Erica, or 

 Calluna vulgaris, is very widely spread all " over Central 

 and Northern Europe to the Arctic Circle, and westward 

 to the Atlantic, from Labrador down to the Azores." So 

 says Bentham in his " Handbook of British FlorSL" 

 Generally growing in this country where furze is plen- 

 tiful, the two plants, with their contrast of golden 

 yellow and purplish-pink, varying to nearly white, 

 give a glow of beauty to the landscape. The most 

 obvious thing to notice with Ling, or Common Heather, 

 is the profusion of flowers on the same stem, arranged 

 tier above tier. This is handy for the bees, and they 

 take some time before they have exhausted the treasures of 

 a single spike. The little flowers have both calyx and 

 corolla deeply cleft into four lobes, which open rather 

 widely, and, with the help of a little magnification, show 

 the projecting pistils closely surrounded by groups of 

 anthers, with little white taUs, standing out in a more or less 

 horizontal circle. The disposition of the flowers is also 

 horizontal, with a tendency of the styles to turn upwards. 

 A pocket-lens will show that the easiest way for a bee to 

 thrust in its long tongue is below the pistil. In doing this, 

 it touches the little anther tails, which act as levers, and 

 spread out the anthers so that their pollen falls upon the 

 insect. 



The best way to display the ling flower under the micro- 

 scope is to fix one quite upright in a bit of beeswax in the 

 middle of a glass slide. The wax, about half the size of a 

 peppercorn, should be softened by heat, but not melted, 

 and the stem of the flower held in a pair of forceps and 

 pressed into it. The object can be illuminated with a 

 lieberkuhn — a very useful instrument, though somewhat 

 out of fashion — or with a bull's-eye lens, or, as I prefer in 

 such cases, by a side silver reflector, mounted on a stand 

 with universal motions, like those given to the bull's- 

 eye. A three-inch objective is a sufficient power, and 

 if the observer's eyes are a pair, and not, as is frequently 

 the case, two odd ones of different focal lengths, a binocular 

 instrument is advantageous. As soon as a bee retires from 

 one flower it goes to another and rubs upon its stigma 

 some of the pollen it previously received. In the course of 

 its operations it will impregnate different flowers on the 

 same stem, and also others on different plants. There are 

 a great number of contrivances amongst plants to secure 

 cross-fertilisation, and when these are adapted to make 

 insects the pollen-carriers the flowers are called entomo- 

 philovis, distinguishing them from those fertilised by wind- 

 borne pollen, which are named anemopfiilous. 



Viewing the ling flowers with a good pocket-lens, or as 

 just described, it is easy to see two rows, or whorls, which 

 both look like corolla segments. The outer one is the 

 calyx, coloured like the inner one, the corolla, and the four 

 calyx-looking green leaflets are bracts. 



If the observer, after becoming familiar with the ling 

 flowers, examines the Scotch heather. Erica cinerea, also 

 called purple heather, it will be noticed that its leaves are 



