Sept. 30, 1880] 



{NATURE 



521 



Digestion in Plants. — Dr. Lawson Tait has recently in- 

 vestigated afresli the Digestive Principle of Plants. While he has 

 obtained complete proof of a digestive process in Cephalotus, 

 Nepenthes, Dioiuea, and the Droscracetr, he entirely failed with 

 Sarracenia and Darlinglotiia. The fluid separated from Drosera 

 binata he found to contain two substances, to which he gives the 

 names " droserin " and "azerin." Dr. Tait confirms Sir J. D. 

 Hooker's statement that tlie fluid removed from the living pitcher 

 of A'efenthes into a glass vessel does not digest. A series of experi- 

 ments led him to the conclusion that the acid must resemble 

 lactic acid, at least in its properties. The glands in the pitchers 

 of Nepenthes he states to be quite analogous to the peptic follicles 

 of the human stomach ; and when the process of digestion is 

 conducted with albumen, the products are exactly the same as 

 when pepsine is engaged. The results give the same reactions 

 with reagents, especially the characteristic violet with oxide of 

 copper and potash, and there can be no doubt that they are 

 peptones. 



Stipules in Onagracle. — Prof. Baillon says {Bull, men- 

 suel. Soc. Lin. de Paris, No. 33) that in the majority of works 

 on descriptive botany, this family is mentioned as charac- 

 terised by the constant absence of stipules, and in justification 

 of this quotes the classical works of Decaisne, Duchartre, 

 Endlicher, and Hooker ; nevertheless he states that the exis- 

 tence of these organs in this family admits of easy proof, not 

 indeed that they ever occur of large dimensions, for then they 

 could not have escaped detection, but still they are present, 

 more commonly as little subulate tonguedike bodies, acute, often 

 red-coloured at the base of the petioles in both opposite and 

 alternate-leaved plants. In Hauya they soon turn black and 

 wither off early. In the fuchsia of our gardens little stipules 

 are often present. In Circea they can also be detected. In the 

 Lopezia of our gardens all the leaves have two very distinct 

 stipules, which indeed have been often referred to in botanical 

 works, and it is the same with Ilaloragia, though Bentham and 

 Hoolcer describe them as here absent. 



A New Green Ciliated Plant. — Under the title of "A 

 New Ciliated Organism furnished with Chlorophyll," Prof, van 

 Tieghem has published {Bull. Soc. But. France, 1S80, p. 130) a 

 memoir of a strange new form. The organism in question was 

 found by Prof. Perrier twice : once at RoscoiT, in sea-water 

 containing alga; and some of the lower animals ; and again at 

 the Museum (Paris), in a little aquarium in the laboratory. It 

 presents the appearance of a gelatinous tremulous mass of a 

 pure green colour ; in outline well defined, spherical or oval in 

 shape, attaining more than a centimetre in diameter, and 

 attached by a portion of its periphery to a large marine alga. 

 At first sight it would be called a Nostoc. Exposed to sunlight 

 it gave out oxygen, so one concludes its colouring-matter to 

 be chlorophyll. On a closer inspection it is seen that the 

 mass is composed of a colourless jelly, scattered throughout 

 which are isolated green points, visible to the unassisted eye, 

 and sufficiently numerous as to give to the whole mass the 

 green coloration distinguishing it, so one would not now refer it 

 to Nostoc. Each little green body is spherical, and measures 

 from three to four-tenths of a millimetre. It is formed of a very 

 finely granular and somewhat dark protoplasm, very uniformly 

 permeated with an amorphous chlorophyll ; neither nuclei nor 

 vacuoles, nor red spot were detected, and the surrounding 

 membrane was very thin. At one place (called the pole) the 

 cell bore a tuft of vibratile cilia which were attached side by 

 side, so as to cover a space more or less large according to age 

 and to allow of independent movements. On the equator 

 at t«'o diametrically opposite points a small hollow in the green 

 mass is seen, and by these passes a band of homogeneous 

 protoplasm which traverses the membrane, turning towards the 

 pole, and in the superior hemisphere dividing on its outer border 

 into fine fringes with vibratile cilia. These cilia are confluen.t at 

 their base, and are not independent in their movements. In 

 process of development the polar cilia become detached (abso- 

 lutely fall ofl), next the lateral moustaches disappear (these seem 

 to be retracted), a continuous membrane covers over all, but the 

 general aspect and dimensions remain unchanged. Later on the 

 cell divides into two (equatorially), next it divides again (perpen- 

 dicularly), and the segmentation continues until there is a family 

 of sixteen rounded-off cells, and the organism has passed through 

 a phase of encystment. Lastly each daughter cell increases in 

 size, separates more and more from its neighbour, gets 

 closed in a fine membrane, and then appears all covered over 

 with cilia. It now escapes into the water and secretes in 



abundance a gelatinous material. The clothing of cilia drops off 

 as the form approaches its adult size : soon appear the polar 

 cilia, next the lateral moustaches ; and so far its life-hi.story is 

 complete. At no phase in its development was either cellulose 

 detected in its cell-membrane, nor starch in its protoplasm. 

 Prof, van Tieghem concludes: — "Is this organism an animal 

 or a plant ? I am not well able to say, and I must add besides 

 that this question, to which formerly so much importance 

 attached, in the actual condition of science, appears to me to be 

 destitute of interest." It is called Dimystax pei-rieri. With 

 every respect to the dictum of so distinguished a botanist as 

 Prof. Tieghem, we venture to call our readers' attention to this 

 strange form, which M. Roze seems disposed to regard as an 

 animal, in the hopes that some of them may assist in determining 

 its proper position in nature. 



PHYSICAL NOTES 



A FRESH measurement has been made by Mr. T. C. Menden- 

 hall of the acceleration of gravity at Tokio, an account of which 

 appears in the American yournal of Science. The experiments 

 were made after the accepted methods with Rater's and Borda's 

 pendulums, the only novelty introduced being that of employing 

 a chronograph in connection with a reliable chronometer to 

 determine the time of vibration of the pendulum. At every 

 sixtieth or hundredth vibration of the pendulum a light break- 

 circuit apparatus placed beneat'n it was raised to just such a 

 height as to be "thrown" by the pendulum at its lowest point 

 of swing, thus enabling its rate to be calculated to the ten- 

 thousandth of a second. Mr. Mendeidiall considers his determi- 

 nations to be more reliable than those of Professors Ayrton and 

 Perry, which were made with a long wire pendulum ; lie revises 

 their calculations, altering their value of "g" from 97974 to 

 97979, and asserts that their calculation of the theoretical value 

 by Clairaut's formula is wrong, and should be 979S0, not 9797 

 (metres). His own determinations give a mean result of 979S4. 



A secondary battery, the electrodes of which consist of 

 porous fragments of gas-carbon, has been devised by M. Heru-i 

 Sauvage. Though inferior in power and durability to a per- 

 fectly "formed" Plante cell whh lead electrodes, this cell would 

 be cheaper, more readdy and rapidly constructed, and would 

 yield a current of longer duration. The action is probably due 

 to the occlusion of the hydrogen and oxygen gases respectively 

 in the pores of the carbon. The inventor recommends that the 

 two plates used as electrodes be kept apart with a simple thin 

 wooden frame. 



Prof. O. N. Rood calls attention to the fact that when the 

 colour of ultramarine blue is mixed with white by the method 

 of rotating disks the tint appears to verge towards violet. 

 Briicke advanced the explanation that what we call white is 

 really a reddish colour. Aubert, on the contrary, regarded it as 

 showing that violet is only a pale shade of ultramarine blue. A 

 series of experiments made with other colours showed that when 

 mixed thus with white green-yellow becomes greenish, and 

 CTreen green-bluish, that full yellow and orange incline to red, 

 and red becomes purplish. These observations accord with 

 neither theory, and Prof. Rood advances none himself. He 

 thinks that the fact as it stands explains why it is impossible in 

 the polariscope to produce a red free from purplish tint, there 

 always being white light mingled with the red rays. 



Prof. J. Trowbridge, in investigating with telephones con- 

 nected to earth-plates the flow of return-currents through 

 "earth," found that at a mile from the Harvard College Ob- 

 servatory the time-signals of the observatory clock could be 

 heard by merely tapping the earth at points fifty feet apart. 



From his recent researches on dilatation and compressibility 

 of gases under strong pressures, M. Amagat derives (Cow/to 

 ren'diis, August 30) the following laws : — I. The coefficient of 

 dilatation of gases (for temperatures not too much above the 

 critical) increases with the pressure to a maximum, then de- 

 creasing indefinitely. 2. This maximum occurs under the 

 pressure with which the product / i- is minimum, where the gas 

 accidentally follows Mariotte's law. 3. It diminishes for higher 

 and higher temperatures, and at length disappears. 4. At a 

 suflicieutly high temperature the compressibility of fluids is 

 represented by the formula / (j- - o) = const. ; a being the 

 smallest volume the mass of fluid can occupy ; this is the limiting 

 law. For each gas o has a special value. 5. For pressures 



