176 



HARDWICKE'S SCIEN CE-GO S S IP. 



HOLLER'S 'NEW DIATOMACEEN TYPEN 

 PLATTE. 



THE veteran microsoopist must unavoidably be 

 struck with the great improvements that have 

 taken place within the last ten years. The attempts 

 at microscopical manipulation of the latter part of 

 the last century, of which specimens may still be 

 found, forcibly remind one of the artistic efforts 

 of our prehistoric ancestors. The old-fashioned 

 plan of mounting between two little discs of talc 

 placed in a slip of ivory about half inch wide and 

 some three inches in length, with six apertures 

 made in it (of these many are still in existence) j 

 was superseded when Canada balsam was intro- 

 duced as a medium for mounting microscopic 



Fig. 115. Specimen of MoUer's Typen Platte, x 100 diameters. 



■I 



objects. The introduction of balsam necessitated 

 the better preparation of the objects themselves, 

 and microscopists adopted various methods for that 

 purpose. The maceration of insects and calcareous 

 material in caustic alkalis, the preparation of 

 sponge spiculse and diatoms by means of hydrochloric 

 and nitric acids, were found to be the most effectual 

 methods for getting quit of extraneous matter. 

 The cleaning and mounting of the Diatomacese, par- 

 ticularly those forms wliich afforded the best tests 

 for the higher powers of the microscope, occupied 

 the attention of those microscopists who were 

 anxious to obtain clean material for mounting. 

 Although by various improved methods the presence 

 ■of vegetable matter was eliminated, micaceous and 

 siliceous sands still remained ; and as a last re- 

 source, diatomists adopted the plan of selecting 

 individual forms from the surrounding debris, and 

 transferring them to clean slides. Not satisfied with 

 this, some mounters arranged the selected forms in 

 symmetrical patterns, and eventually Herr Moller 

 introduced his Tjqoen Platte, in which we had some 

 four hundred species systematically arranged in a 

 space of a quarter of an inch. These exquisite 

 specimens of manipulative skill have now been 

 outdone by his view Typen Platte ; this, although not 

 containing so many forms, is still more remarkable 

 not alone for the beauty of the forms, but also for 

 the method of their arrangement. The following 



short description will perhaps interest those 

 who have not been fortunate enough to have in- 

 spected the "Platte." The objects are mounted 

 between two pieces of thin glass ; these are after- 

 wards set in a brass plate (three and a quarter inches 

 by one and a quarter) ; on the covering glass is a 

 photograph about four mm. square, of eighty 

 circles (ten in a longitudinal and eight in a vertical 

 direction) ; beneath every circle is the name of the 

 object and its author; in the centre of these circles 

 a diatom, and in many cases two are mounted (in 

 order to show front and side views). The accompany- 

 ing diagram will enable the reader to understand the 

 method adopted by this most skilful manipulator. 

 —F. Kitton. 



[I believe these marvellous specimens of the 

 mounter's art may be obtained of Mr. Baker, 244 

 High Holboru.] 



A PLEA FOR OUR GRASSES. 



T SHOULD think that there is scarcely any one of 

 -*- mature years who is not in one sense or another 

 familiar with that particular part of our vegetable 

 kingdom — tlie grasses ; and especially those of them 

 which, on account of the nourishment they afford to 

 man and beast, liave either been acclimatized to, or 

 else have always been common to, the soil and 

 climate of this country from time immemorial. 

 Who, for example, is unacquainted with a field of 

 wheat, of barley, or of rye, when he sees it ! Or 

 who of us can recall a country stroll unassociated 

 with green fields and grassy meadows, or of a 

 country road of unfringed green ? Indeed, you 

 have but to strip the earth of its grassy mantle> 

 and you i-ob it of that hue which, in the landscape, 

 the eye can most untiringly rest upon. In short' 

 these are all scenes to which the eye of the wanderer 

 lias been so naturalized to and familiarized with 

 from earliest years, that without them now the 

 country walk would be shorn of its charms. 



Though the grasses taken comprehensively are a 

 large family, and would take much of our time and 

 investigation before making their acquaintance, 

 botanically speaking, still those really useful grasses 

 to which I am here alluding as constituting much 

 of our meadow and pasture land, form comparatively 

 but a very small percentage of the whole. Eor 

 instance, I dare say most, if not all, are compre- 

 hended under the following genera : Feslaca, Poa, 

 IIolcus, Phleiim, Ilordeum, and Alopecunis — embrac- 

 ing in all not more than about sixteen or eighteen 

 different species. And yet, seeing this, the woniier 

 to me is that more special prominence has not been 

 given to them by our leading botanists ; nay, tli?.*, 

 they have not, in common with our other and more 

 conspicuous flowering plants, been honoured and 

 popularized like them, by being made the subject ot 



