February, 1907 ] 



KNOWLEDGE & SCIENTIFIC NEWS. 



39 



was noted a few minutes after nine o'clock ; totality occurred 

 at seven minutes to ten, and lasted for two minutes, the sun 

 being clear again shortly after ten. As it is also reported 

 that snow was falling throughout totality, it seems probable 

 that most of the observations depending on photographic de- 

 lineation will have been at a disadvantage. Other observers 

 were to be stationed at Tashkend, but no report is as yet 

 available from there. 



Artificial Reppoduction of Lunar Craters. 



M. Gaston Hauet describes an interesting method of pro- 

 ducing artificially variously figured structures which are 

 strongly suggestive of lunar formations. Placing a quantity 

 of wax in a copper vessel heated by a gas flame, as soon as the 

 mass commences to soften a metallic rod moistened with water 

 is plunged into the mass and quickly withdrawn, taking care 

 to close the orifice caused by the insertion of the rod. 



.■\fter a few seconds the gas is turned on stronger, so as to 

 heat the lower part of the wax, and a swelling is seen forming 

 on the surface of the wax. This increases and at a certain 

 stage in its development bursts about its upper part. A jet of 

 steam escapes, and the swelling subsides in the form of a 

 circular ridge with vertical walls. By this the action of the 

 steam inside the mass has been relieved for a time, but after 

 a short interval a similar series of phenomena will be repeated ; 

 if the new swelling happens to come up inside the former 

 there will be formed a central cone very strikingly similar to 

 those so characteristic of true lunar formations. 



BOTANICAL. 



By G. Massee. 



Delayed Germination. 



It is a well-known fact that in the case of many plants the 

 seeds produced by one crop do not all germinate promptly 

 when placed under favourable conditions for doing so. In- 

 stead of this the seeds germinate at irregular intervals, ex- 

 tending through a period of weeks, months, or even years. 

 In other plants the seeds will not germinate under what 

 may be termed normal conditions within a year of their 

 production, and in such instances certain of the seeds show 

 a further marked dela)' in germination. Numerous experi- 

 ments have been made, and suggestions offered as an 

 explanation of this erratic behaviour of seeds. Arthur has 

 described a ven,- interesting case of delayed germination in 

 the seeds of the cockle bur {Xanthivm canadense). The two 

 seeds present in the bur are not exactly counterparts of each 

 other, and are produced at different levels. All the low'er- 

 most seeds germinated the first year after ripening, w-hereas 

 those seeds produced higher up in the bur did not germinate 

 until the second year after ripening, and a few were delayed 

 until the third or fourth year. The author considered that 

 the seed coats did not differ in the two seeds, and suggested 

 that enzymes are produced readily in the lower seeds, and 

 that, therefore, they had food available for immediate 

 germination, w'hereas the upper seeds are only able to form 

 digestive ferments after a considerable period of rest. To 

 determine this question more exactly, Dr. Crocker, of the 

 Hull Botanical Laboratory, U.S..\., carried out a series of 

 experiments with the seeds of various plants, including five 

 kinds of Xanthium, and the dimorphic seeds of Axyris 

 amaranihoides. His conclusions are as follow : — Delayed 

 germination is, as a rule, due to the seed coats rather than 

 to the embryos ; in other words, it is more dependent on 

 mechanical than physiological causes. In soine instances 

 retardation is due to the seed coat excluding the required 

 amount of oxygen. This is the case in Xanihium, but the 

 exclusion of oxygen is much more marked in the case of the 

 upper seeds than in that of the lower ones, hence the differ- 

 ence in time required for germination. .\ high temperature 

 brings about the germination of the upper seeds of 

 Xaiifhium at once by increasing the rate of diffusion of 

 oxygen. In Axyris amaraiifhnides, Aliutilnn, Avicenna, and 

 many other seeds, retardation is due to the exclusion of 

 w'ater by the seed coats. In 7ris seeds the failure to 

 germinate quickly is due to the endosperm and cap arresting 

 the .ibsorption of water, and it is onlv when a certain 



amount of decay in these structures has taken place that 

 germination is possible. 



Seed coats which exclude water are better adapted for 

 retarding germination thdn when oxygen alone is excluded, 

 because of the much greater reduction of transpiration in 

 the first case. 



Hawthorn seeds would not germinate immediately after 

 ripening, even when the seed coats were removed, and after 

 subjection to high temperatures and high oxygen pressures. 

 In this case it was obvious that the changes necessary for 

 germination were located in the embryo ; nevertheless, it is 

 also, to some extent, due to disintegration of the seed coats, 

 because germination in the end is only effected after long 

 exposure to conditions favourable to germination, and not 

 when the seeds are kept dry. 



Treatment of Deteriorated Tea. 



Dr. H. Mann, in Bull. No. 4, of the Indian Tea .\s- 

 soeiation, deals with the gradual deterioration of the tea 

 plant a few years after planting, the bushes rapidly losing 

 their early vigour, and after a period varjing from 10 to 

 20 years they are past their prime. The old method of re- 

 storing such waning bushes by hard pruning is not always 

 successful, because in some instances hundreds, or even 

 thousands, of acres have been collar pruned w hen the bushes 

 are suffering from causes for which collar pruning is no 

 remed}'. The signs of deterioration are a change in colour 

 of the foliage, which assumes an unhealthy, yellowish ap- 

 pearance ; at a later stage the young shoots soon cease to 

 grow, and do not produce leaves. 



.\mong causes of deterioration the principal are, ex- 

 haustion of available plant food in the soil, exhaustion of 

 the bush, and incorrect pruning. A detailed account of the 

 methods by which the primary cause of failure may be de- 

 tected is given ; also the practical methods, including drain- 

 age, manuring, piuning, &c., which seem best adapted for 

 bringing back to a profitable condition much of the tea in 

 India which has now declined from its former value. 



CHEMICAL. 



By C. AiNswoRTH Mitchell, B.A. (^O.kod.), F.I.C. 



Action of Plants on Photogrraphic Plates in 

 the Dark. 



Dr. W. J. Russell has extended his experiments on the 

 action of wood upon photographic plates in the dark (see 

 " Knowledge & Scientific News " Vol. II., 119, 235), and 

 has tried the effect of various seeds, leaves, and roots. He 

 finds that the reducing power is very widely distributed, and 

 that many parts of the plant produce as marked an effect as 

 the wood itself. In the embryo state seeds appear to be 

 inert, but as soon as growth begins the reducing property 

 manifests itself, and continues until the death of the plant. 

 .\\\ leaves were found to have this property, even those lying 

 dead beneath the trees still possessing it, though to a reduced 

 extent. The best method of preparing leaves is to press 

 them between blotting paper under a pressure of one to 

 five tons to the inch ; the liquid absorbed by the paper is 

 also able to act upon the plate. Dr. Russell's hypothesis is 

 that the active agent in the reduction is hydrogen peroxide 

 — at all events, the activity of the plant is comparable with 

 that of hydrogen peroxide. Thus the seed leaf of the runner 

 bean has practically the sanie action on a plate at a distance 

 of an eighth of an inch as a solution of one part of hydrogen 

 peroxide in 100,000 acting at the same distance for the same 

 length of time (24 hoursT. The kernels of nuts are inactive 

 at first, but after exposure to the air produce a verj- dark 

 picture. Castor oil seeds are the least active in this re- 

 spect, and the liquid expressed from them mav be exposed 

 to the air for a month or mure without becoming active. It 

 is not unlikely that some connection m.ay be traced between 

 the drying capacity of the oil in the seed and its reducing 

 power. The outside shells of seeds are quite inactive. In 

 the cocoanut shell, for instance, the light-coloured portion 

 has no effect upon a plate, whereas the darker parts are 

 very active. In many cases the roots of plants have a verj- 

 strong reducing action, the root of the Scotch fir, for ex- 

 ample, giving a picture similar to that produced by the 

 wood . 



