232 HALF-AN-HOUR 



larger structures P E. argiis is especially interesting in this 

 respect ; and without a good deal of the knowledge (only to be 

 gained by experience), it is somewhat difficult to mentally unite all 

 the various pieces into which these Diatoms break up. This is 

 scarcely distinct as a species from E. ocellata^ under which name 

 some of the specimens on this slide might be placed. 



Pollen of Mallow (PL 40). — This is a remarkably fine speci- 

 men ; its beauty and interest recommend it to microscopists of 

 every degree of attainment, so that it is no wonder it is a universal 

 favourite wherever introduced. I know nothing better for showing 

 to the uninitiated the beauteous appearance of the fine dust so 

 hastily brushed from flowers, so thoughtlessly regarded by most, 

 yet so essential to the economy of the plant. The union of the 

 staminal filaments into a tube, whence the name " monadelphous^^ 

 is well shown here ; at the base of this tube note the rough hairs, 

 whose use is probably to retain the precious dust as it falls, that 

 none be lost. Most anthers are "two-celled," or '■'■ biloadar ;'^ 

 capital examples of this will be seen presently in those of tulips or 

 lilies. The anthers of MalvacecE, however, depart from this type 

 (it is supposed by suppression of one of the lobes), and hence are 

 regarded as " imiloadar.^' The form of pollen seen here, " sphe- 

 rical," with the " outer coat granular and spiny," and " pores scat- 

 tered irregularly over the surface," is one of the characteristics of 

 the Mallow tribe. It would be desirable to know from what 

 species this came, and how it was secured in such prime condition. 

 I should expect to get it by slitting the tube into half with a sharp 

 knife very soon after opening, popping on to a slip with cover, but 

 without other pressure, and keeping in a moderately damp place 

 to favour the opening of the anthers, and yet retain the pollen as 

 it escaped. I have seen pleasing modifications in the mode of 

 mounting this object, the petals being retained, and shown so far 

 as the size of the glass would allow. This, when skilfully managed, 

 makes a desirable addition to its beauty. It may be remembered 

 that one of the Pollen-baskets in the slide of " Hind Limbs of 

 Humble-Bee," shown by R. H. Moore, had a mass of Malvaceous 

 pollen in it, probably from the hollyhock, as that is a favourite 

 flower with them. From the Pollen-basket of the other limb this 

 had been removed. 



Parasite of Dyticus (PI. 41). — Probably few of us but are 

 familiar with a beautiful little scarlet mite, which looks, as it goes 

 merrily bobbing about in the water, like an animated bead of the 

 most brilliant red coral. Its name is HydracJina glohda. Vora- 

 cious enough after reaching maturity, its early life is just one act 



