332 



NATURE 



[August 4, 1898 



Taking the whole period from Gledhill's first observation on 

 November 14, 1869, when the spot was central at about 

 loh. 50m., to one obtained at Bristol on June 7 last, at gh. 20m., 

 we shall find the interval covered 10,431 days 22 hours and 

 30 minutes, and that 25,218 rotations were performed with a 

 mean period of 9h. S5m. 377s. 



In addition to the variation exhibited in the diagram, there 

 have been some minor changes in the motion of the spot. 

 These could, however, only be satisfactorily worked out from 

 the most accurate observations and by determining the rotation 

 periods for short intervals. 



As to the question whether the red spot is identical with 

 markings seen in 1857, 1858 and 1859, the matter is open to 

 doubt, for there seems to be a great lack of corroborative 

 observations between i860 and 1869. The objects delineated 

 by several skilled observers about forty years ago were some- 

 what similar ,in position and form to the red spot of recent 

 years, and afford strong presumptive evidence of identity. We 

 have had the spot continuously before us for twenty years, and 

 there can be no doubt that its existence can be traced back to 

 1869. We ought to be able to go back another ten years and 

 affiliate it with the elliptical markings which were drawn by 

 Dawes, Huggins and others in the region immediately south of 

 the great equatorial belt in 1857, 1858 and 1859, but there is 

 an absence of suitable observations along the interval, and 

 though it is easy to infer that the various objects were identical 

 the fact cannot be demonstrated. 



Had observations been more numerous, we should perhaps be 

 able to put our hands on a complete series of records of the 

 red spot extending back for a very long period. It must be 

 remembered that some years ago the planet was so much 

 neglected that a conspicuous feature might easily escape notice 

 •during the whole of a favourable apparition. Thus the ellipse 

 of 1869-70 was only seen by Gledhill and Mayer, though Jupiter 

 was a splendid object at about that period. The fact that an 

 object was not seen is, therefore, far from being conclusive 

 evidence of its non-existence. 



Though there is reasonable proof that the marking drawn by 

 Russell and Bredichin in 1876 was the same as that which 

 attracted so much notice two years later, it is curious what 

 became of it in 1877. Bredichin gives fifteen drawings of the 

 .planet's appearance in the summer of the latter year (see Annales 

 de r Observatoire de Moscoii, vol. iv., 1878), but there is no sign 

 of the red spot. The object, if it existed during that opposition, 

 may have been temporarily obscured by more highly reflective 

 material lying above it. It seems to have been much involved 

 with the belts in the southern hemisphere before 1878. Mr. H. 

 ■C. Russell remarks that he first saw it separated from the belts 

 on July 8, 1878, and was not long in recognising it as an old 

 friend which he had frequently seen in 1876. 



Many of the markings on Jupiter are probably formed by 

 materials evolved from the actual surface of the planet, which 

 afterwards become floating masses in the outer region of the 

 atmosphere. Their longitudes do not probably long coincide with 

 that of the original seat of disturbance, for they will fail to keep 

 pace with the exceedingly rapid motion of the sphere, and must 

 exhibit a retardation similar to that so well pronounced in the 

 • case of the red spot. The latter has proved itself a very special 

 object with a durableness which does not seem to have charac- 

 terised other markings. There were "new red spots" in 1886 

 and 1 89 1, but they did not last long. The majority of the 

 Jovian markings appear to be somewhat transient and irregular 

 in their apparitions, and certain zones of the planet would seem 

 favourable to the production of markings having an individuality 

 •of aspect. 



The true rotation period of the actual sphere of Jupiter still 

 awaits accurate determination. An occasion might, however, 

 •present itself for this element to receive satisfactory investiga- 

 tion. If the spots are really due to eruptions from the planet, 

 and if these should be sustained over periods sufficiently long 

 for the purpose intended, then a string of spots might be formed 

 along a zone, and the time taken to complete the circumference 

 might give data for ascertaining the true rotation period if the 

 retardation of the markings on arriving in the outer atmosphere 

 were allowed for. Thus, in 1880-81 I watched the formation 

 of a complete girdle of spots in about ninety days ; and had the 

 distension taken place always on the preceding side, the 

 materials would have been obtained for finding the correct 

 period, for the observed rotation of the spots was 9h. 48m. But 

 ithe objects appeared to extend themselves both east and west, 



though the spreading out on the following side may have 

 been due to an increase in the slackening motion, rather than 

 to the formation of new spots. Phenomena of this character 

 obviously off'er important features for discussion. Whenever an 

 outbreak of spots takes place, it becomes necessary to learn the 

 direction and rate of its longitudinal distension ; for such inquiries 

 may usefully increase our knowledge of the physical condition 

 of Jupiter, and supply us with a more precise value for the 

 rotation period. Gur previous acquaintance with this element 

 depends upon atmospheric phenomena, and must be to some 

 extent in error, for the markings display proper motions differing 

 among themselves to the extent of nearly eight minutes, and in 

 nearly every case the rate of velocity appears to vary in an 

 irregular manner but generally lengthening with the time 



W. F. Denning. 



NO. 



I 501, VOL. 58] 



THE GERMINATION OF HORDEUM 

 VULGARE.i 

 'X'HE work described in this paper is a continuation of a 

 •^ previous research by Mr. Horace T. Brown and Dr. G. II. 

 Morris published in i%()0 [Jottr. Che>ii. Soc, vol. Ivii. p. 458), 

 dealing with the respective influences of embryo and endosperm 

 in the alteration of the reserve-starch and celkdose for the 

 requirements of the young plant during germination of seeds of 

 the Graminece. The seeds of various species were examined, 

 but the main results were obtained with Hordeum vulgare ; the 

 observations made in this later work are also almost entirely 

 confined to this species, and there can be but little doubt that 

 the results will be found applicable to the Graminete generally. 



It was shown in the earlier paper that the first changes in the 

 endosperm during incipient germination are disintegration and 

 ultimate dissolution of the membranes of the amyliferous cells, 

 this being followed by erosion of the contained starch-granules. 

 These phenomena suggested that the action is due to the in- 

 fluence of the embryo, and not to any autonomous action of the 

 endospermous cells themselves. 



While investigating this point, it was found that a carefully 

 excised embryo can exist independently of the seed, if supplied 

 with suitable artificial nutriment in the form of certain carbo- 

 hydrates, its own proteids yielding sufficient nitrogen for the 

 production of plantlets of considerable size. It was also found 

 that the embryo can be transferred from the endosperm of one 

 seed to that of another, and that healthy plantlets are produced 

 under these artificial conditions. 



In this manner it was shown that an excised embryo can 

 induce in starch-granules an action alike in kind and degree to 

 that produced by an embryo growing zn situ on its natural 

 endosperm, as in normal germination. It was found that the 

 columnar epithele of the scutellum can secrete a very active 

 amylohydrolytic enzyme, and project this into the endosperm or 

 any artificial' nutriment in intimate contact with itself. This 

 embryonic activity was, however, recognised not to exclude the 

 possibility that the endospermous cells might participate in the 

 dissolution of their own reserve-materials. To ascertain how far 

 such co-operation might exist, degermed seeds were studied 

 when placed in conditions allowing rapid removal of any pro- 

 ducts of change. The same end was also obtained by grafting 

 a living embryo from one grain on to the endosperm of another, 

 that had been'so treated, so as to destroy presumably all potential 

 vitality of the endospermous cells. Since living embryos in- 

 duced in these supposititiously dead endosperms all normal 

 changes of depletion, and since no autonomonous changes were 

 observed in the degermed endosperms not attributable at that 

 time to adventitious micro-organisms, the idea of residual vitality 

 in the endosperm as a condition of its depletion seemed super- 

 fluous. 



Since 1890, Griiss, Hansteen, and others, have confirmed the 

 conclusions formed in 1890, that the embryo can secrete enzymes, 

 but Pfefi"er, Hansteen, Griiss, and Puriewitsch have strongly 

 contested the view that the endosperm has no autonomous 

 power of self-depletion. These latter observers state that the 

 amyliferous cells of the endosperm have distinct power of digest- 

 ing their own reserves, this function being quite independent of 

 any induced action of the embryo, and due to residual vitality. 



The present work is the result of a re-examination of the 



1 " On the Depletion of the Endosperm of Hordeum vulgare during 

 Germination." By Horace T. Brown, F.R.S., and F. Escombe. (Read 

 before the Royal Society on March 3.) 



