66 



NATURE 



[November i6, 1899 



vol. Ixv., 1899, p. 158). The genus Onygena comprises six 

 species, all very imperfectly known, remarkable for their growth 

 on feathers, hair, horn, hoofs, &c., on which their sporocarps 

 appear as drumstick-shaped bodies 5-10 mm. high. A cow's 

 horn thoroughly infested with the mycelium of 0. equina 

 yielded material for the investigation ; the author not only veri- 

 fied what little was known, but was able to cultivate the fungus, 

 to trace its life-history, and to supply some details as to its action 

 on horn. The development of the sporocarps, the structure, 

 germination and biology of the chlamydospores were dealt with ; 

 also the details and development of the asci and the germination 

 of the ascospores. Prof. Ward expressed the view that no trace 

 of any morphological structure comparable to sexual organs 

 could be discovered, though many points suggest the alliance of 

 this fungus with Erysipheae and the Truffles. 



Mr. R. H. Biffen (Cambridge) presented an account of \Bul- 

 garia polymorpha _ (Wettstein) as a wood-destroying fungus. 

 Bulgaria polyniorpha is stated by Ludwig to be parasitic on oak. 

 The author has examined its anatomy, and studied it in pure 

 cultures on wood and in food- material. The white early growth 

 soon becomes bright orange ; small rounded elevations are 

 afterwards formed, which are incipient reproductive bodies. 

 The action on wood was examined in some detail. The fungus 

 grows better on oak than on pine. The lignified wood -elements 

 are de-lignified. Details as to the reactions in various stages of 

 its destructive action are dealt with in the paper. The author 

 does not regard the fungus as of great importance as a wood- 

 destroying organism in this country. 



Mr. A. Howard (Cambridge) described some recent work on 

 a disease of Tradescantia. 



During the summer it was found that two species of Trades- 

 cantia, growing in greenhouses, were being attacked by a 

 fungus. Diseased leaves and stems were in many cases found 

 to be covered with long white conidiophores. Pure cultures 

 were made of the parasite, which proved to be a species of 

 Botryosporium. Some difficulty was experienced in obtaining 

 this form free from another fungus, a species of Cladosporium. 

 It was found in the case of the naturally growing host plants 

 that infection started either on the upper side of the leaf or 

 from the margin. Tangential sections of the upper epidermis of 

 the leaf, when grown in hanging drops, showed in all cases 

 hyphae on the epidermis, which gave rise to the same species of 

 Cladosporium as that mentioned above, occurring as a weed in 

 the Botryosporium cultures. The development of this Clado- 

 sporium was then followed out from a single spore by the 

 hanging-drop method, and infection experiments were made 

 which proved successful. 



Prof. Potter (Newcastle) read a paper on a bacterial disease — 

 white rot — of the turnip. 



The author found in the early autumn numerous turnips, 

 whose roots, when fully grown, became completely rotten. The 

 rotten portion presents a white glazy appearance, and the tissues 

 are reduced to a soft pulpy condition ; the cell-walls are much 

 swollen, faintly stratified, and separate from each other along 

 the middle lamella. The decaying mass is infested with bacteria, 

 but the most careful microscopic search has failed to detect any 

 fungoid hyphae. The rottenness can be readily introduced into 

 a sound root by inoculation at a wounded surface ; from this 

 point the decay spreads rapidly through the root, the leaves 

 gradually turn yellow, and in about fourteen days the entire plant 

 has succumbed. Among the bacteria found in the rotten mass 

 one has been isolated, which, when sown from a pure culture on 

 turnips, under sterile conditions, induces all the characteristic 

 effects of the " white-rot." 



The bacterium, which has a single polar flagellum, was de- 

 scribed by the author under the name Pseudomonas destructans. 

 It occurs in the form of short rods about 3ju long by 'Siu broad, 

 with one polar flagellum ; it rapidly liquefies gelatine, forming 

 circular whitish colonies. The organism is parasitic on turnips, 

 potatoes, carrots, but not on beetroot, forming a cytase. 



Mr. Harold Wager gave an account of the phosphorus- 

 containing elements in yeast. By using the method of Macallum 

 for the determination of phosphorus in cells, which consists in 

 the formation of a precipitate by means of a nitric acid solution 

 of ammonium molybdate and subsequent coloration by means 

 of the reducing agent phenylhydrazine hydrochloride, the 

 author has been able to demonstrate that the phosphorus resides 

 in a definite organ of the cell, which has been described as a 

 nucleus by various observers. This affords, therefore, additional 

 evidence in favour of the nuclear nature of the body. 



% Prof. Ward contributed some notes on methods for use in the 

 culture of algae. The notes were of the nature of suggestions, 

 the experiments being still in progress ; but the author gave an 

 account of the work in hand with a view to interest those 

 engaged in investigations involving the cultivation of algaj. 



If agar is swollen in dilute acetic acid, and then wa.shed very 

 thoroughly, it can be used, mixed with the necessary culture 

 fluids, as a convenient medium for the growth of some algae, as 

 Beyerinck had already observed. 



The author has succeeded in separating algae by the following 

 methods : — 



The algas are shaken up in a sterilised nutritive mineral solu- 

 tion, mixed rapidly with silica jelly, also sterilised, and poured 

 into glass dishes. With species of Oscillaria and of Palmella 

 the author has observed growth in hanging drops of this silica- 

 jelly medium under high powers. 



Another device is as follows ; — Shake the algae up in the 

 nutritive solution and rapidly mix with sterilised plaster of paris 

 and pour into dishes. The fixed algae grow in situ in some 

 cases, but others appear to be too sensitive for such treatment. 



Experiments have also been made as follows, with some 

 promise of success : — The algae are shaken up in the culture 

 medium, and a large quantity of lime-water quickly added. 

 Carbon dioxide gas is then passed rapidly through, and the 

 algae are thrown down with the precipitate of calcium carbonate ; 

 this is poured into dishes as if it were plaster of paris. Perhaps 

 this method could be utilised in the study of calcareous algae, 

 but with some forms it appears too drastic. One drawback is 

 the difficulty of obviating the use of unsterilised materials. 



In illustration of the application of the methods. Prof. Ward 

 described some observations of the growth of Oscillaria tener- 

 rima in hanging drops of silica-jelly. The growth of a single 

 filament was followed for more than a week, and the curve 

 showed that growth ceased during the hours of darkness, and 

 was coincident with assimilation during the day. The author 

 also obtained "light-figures" by exposing plates of green algae, 

 covered with stencil letters, to various intensities of daylight 

 reflected from mirrors. When the light was not too strong, a 

 green letter on a colourless ground was formed, but with intense 

 illumination the exposed algae were killed, while those in the 

 covered area, illuminated only by diffuse light, were able to 

 grow ; the result was a colourless letter on a green ground. 



Mr. W. G. Freeman (Royal College of Science) contributed 

 a note on the Anabaena-con^aXxixri^ roots of some Cycads. The 

 author drew attention to the manner in which the roots occur 

 on various species of Cycads growing in very poor soil in the 

 Royal Botanic Garden, Peradeniya. In most cases a dense 

 coralloid mass of specialised fleshy roots was found encircling 

 the stem ; in others — e.g. Macrozamia Perofskiana — normal - 

 looking lateral roots ran horizontally beneath the ground, giving 

 off the special algae-containing roots at intervals. These primary 

 lateral roots may be apogeotropic for a time, but after bearing 

 the Anabae7ta-cowtzxKm^ masses they resume a normal habit 

 and grow downwards. 



Mr. E. J. Butler (Queen's College, Cork) communicated a 

 note on a mixed infection in Abutilon roots. The roots of 

 seedlings of Abutilon hybrids in the plant-houses of Queen's 

 College, Cork, presented tuberoid enlargements due to, at 

 least, two parasites— a Nematode and an Ascomycete. (i) The 

 Nematode is a Heterodera, apparently not identical with H. 

 Schachtii. All stages of the life-history were worked out by 

 the author. (2) The Ascomycete is a new Thielavia, which 

 the author named T. Hartogii, differing from T. basicola in 

 its more abundant sporidia in each pseudo-sporangium and dark 

 green chlamydospores. (3) A fungus, coexisting with (i) and 

 (2), whose unseptate hyphoe, " cellulose " wall and reproductive 

 bodies recall Peronosporeae, has been partially studied. 



Pteridophyta. 



Prof. Bower read a paper on fern sporangia and spores, in 

 which he gave an account of the results of his recent investiga- 

 tions described at a meeting of the Royal Society on April 20 

 {Proc. Roy. Soc, vol. Ixv. p. 96, 1899). Prof. Bower suggested 

 the following classification of the ferns based on (i) the relative 

 time of appearance of sporangia of the same sorus, (2) certain 

 details of structure of the sporangium and its stalk, (3) the orient- 

 ation of the sporangia relating to the whole sorus, (4) the 

 potential productiveness of the sporangium as estimated by its 

 spore-mother cells, and the actual spore-output. 



NO. 



1568, VOL. 61] 



