144 PR0QBES8 OF MICROSCOPICAL SCIENCE. 



habit ; and as he considers that Empusina, Saprolegnia, and Achlya — 

 members of the Protista — are the same organisms, living under 

 different physical conditions, he names the old form Pcdceaclilya 

 penetrans; and he believes that it entered the wall by the spores 

 fixing on to the organic matter, and growing by its assimilation, and 

 that carbonic anhydride was evolved. He considers that this acid, 

 assisted by the force of growth and the movement of the cytioplasm, 

 are sufficient to account for the presence of the tubes. Finally, the 

 author draws attention to the probable similarity of external conditions 

 in the Silurian and present times, and to the wonderful persistence of 

 form of this low member of the Protista. 



Dr. Woodward on the Spurious Lines of Diatoms. — The ' American 

 Naturalist,' in its January number (which is the first of a new series, 

 and is really an admirable number), states, that at the Philosophical 

 Society of Washington recently Dr. Woodward, of the Army Medical 

 Museum, gave an account, illustrated by photographs and illuminated 

 photographic pictures thrown upon a screen, of spurious lines, noticed 

 by Dippel, and more lately in a British periodical, as genuine, seen on 

 certain diatoms. The species FrustuUa Saxonica has transverse lines 

 of extreme fineness, and longitudinal lines had been described by Dipj)el 

 and others, some asserting that the latter were coarser, and others that 

 they were finer than the transverse ones. Dr. Woodward showed very 

 clearly by his illuminated slides, enlarged on the screen 45,000 

 diameters, that the longitudinal lines appeai*ed not only on the diatom, 

 but also on the space external to it, and similar lines appeared about 

 specks of dirt on the plate. These could be varied in coarseness by 

 different illuminations of the object. Hence he concluded that they 

 were spurious, and caused by diffraction of light from the midriff, or 

 the edge of the diatom, or any other object in the field. He remarked 

 that the existence of real lines could be determined by the fact 

 that they did not vary in number under varying illuminations or 

 focussing ; they were either seen uniformly or not seen at all. 



Belations between Plants and Animals. — This subject has been 

 recently lectured on by Prof. Huxley at the Eoyal Institution, A 

 full report of the Professor's remarks will be found in ' Macmillan's 

 Magazine ' for February. After describing very fully some remark- 

 able monads which were found in an infusion made by Prof. Tyndall, 

 and referring in most complimentary terms to the papers published in 

 this Journal by Mr. Dallinger and Dr. Drysdale, the Professor con- 

 cluded by observing that keen and patient research induces the belief 

 that such an insensible series of gradations leads to the monad that it 

 is impossible to say at any stage of the progress — Here the line 

 between the animal and the plant must be drawn. It is therefore a 

 fair and probable speculation, though only a speculation, that as there 

 are some plants which can manufacture protein out of such apparently 

 intractable matters as carbonic acid, water, nitrate of ammonia, and 

 metallic salts, while others need to be supplied with their carbon and 

 nitrogen in the somewhat less raw form of tartrate of ammonia 

 and allied compounds, so there may be yet others, as is possibly the 



