HARDWICKE'S SCIENCE-GOSSIP. 



25b 



or less perished, but it is not difficult to find traces 

 of antheridia in the specimens. 



For comparison, the original figure of artotrogus 

 (fig. 161) is here exactly reproduced to the same scale 

 as my drawings, from vol. i. of the Journal of the 

 Royal Horticultural Society, to show the similar 

 nature of the bodies illustrated. Since this was 

 engraved, Mr. Berkeley has kindly forwarded Dr. 

 Montague's original drawings to me for examina- 

 tion, and I may as well say they contain many more 

 threads and oogonia than are shown in this cut, and 

 they are also more like my organisms now brought 

 forward. As for some of the bodies being shown as 

 if within the threads by Dr. Montagne, I consider 

 this of little moment, as the oogonia are at times 

 almost or quite sessile, and consequently, when seen 

 in some positions, they put on an appearance of 

 being within the mycelium, whilst in reality they 

 are upon or under it. As for the echinulate body 

 at o, described as a "mature spore," it is not 

 exactly like Dr. Montagne's original drawing, which 

 is shown as furnished with a thick wall, and there 

 are no " mature " spores in his specimens. After 

 a most careful and searching examination of the 

 latter, I can find no such bodies, but there are 

 several spores on the two mica slides which put on 

 a spuriously echinulate appearance, which is owing 

 to the collapse of the coat of cellulose, as suggested 

 by me as a possibility when I read my first paper. 



It will be observed there is a little difference in 

 size between my oogonia (fig. 163) and those copied 

 from the Journal of the Royal Horticultural So- 

 ciety; this is because the figures in the latter are 

 somewhat incorrect. When the actual specimens 

 are examined and measured side, by side they are in 

 every w r ay identical. 



Mr. Berkeley has also most obligingly sent me a 

 specimen of another (new species ?) of Artotrogus, 

 found in decayed turnip by Mr. Broome in 1849. 

 Here the threads and semi-mature bodies are in the 

 same style as the oogonia and threads from the 

 potato, and the mature spore is not truly echinulate ; 

 it is globular, with a slight tendency to an oval 

 shape, and is covered with warts. It is probably 

 the resting spore of Peronospora parasitica, the pest 

 of the cabbage. 



In figs. 162 aud 160 are given copies of the oogo- 

 nium and antheridium of Peronospora umbel liferarum 

 and P. alsinearum, enlarged from De Bary to the 

 same scale as the other figures, to show the close 

 similarity in size and habit. 



{To be continued.) 



"The Swallows, loth to leave us, linger on far 

 into the autumn, and only bid us adieu when they 

 miss the genial influence of the sun's rays, and can 

 no longer find a sufficient supply of food." — Hart- 

 inefs Summer Migrants. 



MICROSCOPY. 



Seeds as Opaque Objects for the Micro- 

 scope.— "F. E. Fletcher" and others will find the 

 following seeds good microscopic objects for low 

 powers : — Portulaca oleracea, Silene pendula, Loasa 

 aurantiaca, Paulonia imperialis, Lychnis jloscuculi, 

 Antirrhinum majus, Eschscholtzia termiflora, Stellaria 

 media, Galinsoga parviflora, Nemesia compacta* 

 Hypericum pulchrum, Sphenogyne speciosa* Glyce- 

 rine is, perhaps, one of the most troublesome media 

 to keep within the bounds of the cell ; but the fol- 

 lowing cement will, if properly applied, do so. 

 Gold-size, white-lead, red-lead, and litharge ; 

 it must be made thin enough to work freely with 

 the brush. This cement should only be made in 

 sufficient quantity for present use, as it soon hardens 

 and becomes useless. Care must always be taken 

 to cleanse the slide and cover of any glycerine that 

 may have escaped: the cement should be used in 

 successive layers, allowing the first to harden before 

 applying a second. I am informed that the flake 

 white (mixed with oil) sold iu tubes for the use of 

 artists, to which a little dammar varnish should be 

 added, is also an excellent cement. — F. K. 



Seeds for the Microscope. — The following 

 small seeds will prove interesting objects under a 

 low power and good reflected light -.—Digitalis pur- 

 purea, Antirrhinum majus, A. oroutium, Linaria 

 cymbalaria, L. purpurea, L. vulgaris, L. minor, 

 L. spuria, and the seeds of Scrophulariacets gene- 

 rally. The Bignoniacete are interesting, on ac- 

 count of the varying development of a beautiful 

 winged appendage — e. g. Paulonia imperialis t 

 Eccremocarpus scabra, Nemesia versicolor, Lopho- 

 spermum scandens, &c. The Ranunculacece furnish 

 many beautiful specimens ; as, Nigella damascena, 

 Cimicifuga racemosa. The Papaveracece are also 

 interesting, as also the genus Campanulas, and the 

 whole of the Caryophyllacese. There is plenty of 

 opportunity for research, as only a hundred or two 

 of minute seeds, so far as the writer knows, have 

 been examined. — W. T. S. 



Glycerine Mounting.— Glycerine is difficult to 

 keep in a cell, but it can be doue effectually by 

 careful manipulation. The proper cement is the solu- 

 tion of shellac in wood naphtha, known as " liquid 

 glue" or "patent knotting varnish." The object 

 being placed in its cell, and the cover put in posi- 

 tion, the surplus glycerine is to be carefully cleared 

 off, so as not to disturb the cover; first, by absorb- 

 ing as much as possible by the delicate application 

 of shreds of blotting-paper with the forceps, after- 

 wards clean off as much glycerine as possible with a 



"One Thousand Objects for the [Microscope," by M. C. 

 Cooke, gives figures and descriptions of many kinds of seeds 

 and pollens. 



