214 



NATURE 



{ywie 30, 1887 



unnatural conditions. The temperature registered on the death 

 of the fish named exceeded the highest and lowest degrees 

 given below, which are, as already stated, intended to indicate 

 the temperature of water in which they can be maintained in 

 aquaria. 



Marine Fish. 



Fresh-water Fish. 



It will thus be seen that the dogfish, mullet, conger, skate, 

 flounder, bass, cod, trout, catfish, pike, and carp are extremely 

 hardy, and can exist in both a high and low temperature, ranging 

 from 34° to 71°. On the other hand, the gurnard, wrasse, bull- 

 head, sole, bream, crayfish, blennie, perch, dace, tench, minnow, 

 chub, roach, and gudgeon show themselves sensitive to extremes 

 of temperature. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, June 16. — "On the Tubercular Swellings 

 on the Roots of Vicia Faba." By H. Marshall Ward, 

 Fellow of Christ's College, Cambridge, Professor of Botany 

 in the Forestry School, Royal Indian College, Cooper's Hill. 



In this paper the author gives a detailed account of his in- 

 vestigations, of which the following is a short abstract. 



The curious tubercle-like swellings on the roots of Vicia and 

 other Leguminosce have long been a puzzle to botanists and 

 agriculturists. They have even been described as normal struc- 

 tures by some observers. The general opinion, however, has 

 been that th^y are not so. Erikssen and Woronin at one time 

 thought they contained Bacteria ; Kny and others ascribed them 

 to a Myxomycete ; Frank and others had also observed certain 

 extremely minute hyphse in their tissues ; but no one had been 

 able to discover the connexion between the tubercles and a 

 fungus. 



By special methods of culture and observations extending 

 over some time. Prof. Marshall Ward has discovered that the 

 tubercles of Vicia Faba contain a fungus of a very definite 

 kind, and be exhibited preparations showing the structure of 

 the tubercks and fungus, and the entrance of the infecting 

 hypha into the root-hairs of the plant : this infecting hypha 

 passes down the root-hair and across the cortex, and then breaks 

 up into finer hyphae, from the ends of which are budded ex- 



tremely minute germ-like bodies, which Woronin mistook for 

 Bacteria. They are not Bacteria, however, but present more 

 resemblance to the buds discovered by Brefeld in the Usti- 

 laginecE. 



The author has succeeded in artificially infecting the roots of 

 beans with the fungus, and finds that the minute infecting spores 

 are to be met with in all kinds of soil, so that it is a matter of 

 some difficulty to obtain roots which are not attacked by the 

 fungus. This can be done by burning the soil, and by means 

 of pure water-cultures. 



The affinities of the fungus are with the Ustilagiucce, and the 

 case is a very remarkable instance of symbiosis. 



"On the Structure of the Mucilage Cells of Blechnuni occi- 

 dcntale, L., and Osmunda regalis, L." By Tokutaro Ito, 

 F.L.S., and Walter Gardiner, M. A. Communicated by Prof. 

 M. Foster, Sec. R.S. 



The growing point of many ferns is found to be covered with 

 a slimy mucilage, which arises from hairs situated on the palae 

 and the leaves ; this mucilaginous secretion serves a most im- 

 portant physiological function, in that it readily takes up and 

 retains water, and thus keeps the young bud moist, and at the 

 same time it prevents excessive transpiration. The authors 

 investigated two cases of mucilaginous secretion, viz. Blechnutu 

 occidenlale, L., and Osiminda regalis, L. They find that the 

 mucilage arises from the protoplasm only, and not from the 

 cell-wall, and that the whole process is distinctly intraproto- 

 plasmic. They point out that the structure of mature mucila- 

 ginous gland is wonderfully like that of certain secretory animal 

 cells recently investigated by physiologists ; and they find that 

 in the glandular cells of the ferns mucilage is secreted in the 

 form of drops, and that each drop is further differentiated with 

 a ground substance (gum mucilage), in which are embedded 

 numerous spherical droplets (gum). 



The secretion commences by the breaking down of a portion 

 of the innermost layers of the endoplasm of a number of con- 

 tiguous but isolated areas, and the result of these cataboiic 

 changes in the protoplasm is the formation of small but rapidly- 

 growing mucilage-drops. The first formation takes place just 

 beneath the free surface, equally around the whole cell- cavity, 

 and the phenomenon steadily continues from within outwards, 

 producing new drops basipetally, until the whole of the endo- 

 plasm has taken part in the process. The cell is now full of 

 isolated drops, each inclosed by a portion of the delicate proto- 

 plasmic framework which still remains. A remarkable sequence 

 of changes occurs in the drops themselves. At their first forma- 

 tion they are watery and by no means well defined ; they shortly 

 become denser, and then in the drops themselves a delicate 

 reticulation may be observed, which gives way to the appearance 

 of numerous minute and brightly shining droplets, all separate 

 and distinct. The result of their observations makes the authors 

 disposed to believe that during secretion the protoplasm gives 

 rise to a gummy mucilage, and the latter undergoes further 

 differentiation into a ground substance, which still retains its 

 mucilaginous character, and into a gummy substance which is 

 present as a number of isolated spherical droplets. Excretion 

 takes place by the rupture of the cell-wall, all that remains in the 

 cell being a layer of endoplasm with the disintegrated nucleus. 



In the case of animal glands, t'.^''. serous and mucous salivary 

 glands, the state of active secretion is followed by a resting- 

 period, during which the protoplasm grows, forms new hyaline 

 substance, and this again produces new granules. The authors 

 believe that a series of changes essentially similar in character 

 occur in plant- cells also. Usually speaking, plant-cells are 

 incapable of such active and repeated secretion, and in many 

 cases, e.g. Bkchnu?/i and Osmunda, the secretion-changes occur 

 in the cell once and for all, and then the cell dies ; in other 

 instances, however, e.g. the glands of Diomca, it appears exceed- 

 ingly probable that the phenomena which accompany the 

 repeated secretion are quite similar to those which happen in so 

 many animal cells. They believe that in their main features 

 the phenomena attending the formation of the secretion are very 

 wide-spread, and limited neither to the ferns nor to the par- 

 ticular case of the secretion of mucilage. 



Royal Meteorological Society, June 15. — Mr. W. Ellis, 

 President, in the chair.- — The following papers were read : — 

 Amount and distribution of monsoon rainfall in Ceylon generally, 

 with remarks upon the rainfall in Dimbula, by Mr. F. J. Waring. 

 The principal feature in Ceylon as determining both the amount 

 and distribution of rainfall is a group of mountains situate in the 



