Staining Small Objects. 105 
determining factor in this movement. For in the cowslip the very 
opposite occurs. The flowers, at first pendant, offer greater 
facilities as far as self-pollination is concerned to the long-styled 
forms, but later on the flowers become erect and thus in the 
absence of cross-pollination the short-styled forms will have ample 
opportunity to be self-pollinated. . 
From the observations I have made on the primrose I feel 
convinced that it is both regularly visited and cross-pollinated by 
insects under favourable climatic conditions, but that like most 
flowers adapted to the visits of insects, it is provided with 
efficient means for self-pollination and these are important to a 
plant flowering at so early a period of the year when the visits 
of insects may be precarious. 
ON A NEW METHOD FOR FACILITATING THE STAINING 
OF MICROSCOPICALLY SMALL OBJECTS, 
By V. H. Blackman, M.A. 
mHERE is a great need for a really satisfactory method of 
| dealing with microscopically small objects so that they can 
be stained by the most modern methods and handled as easily as are 
microtome sections fixed to a slide. 
The obvious method, by decantation, in which the objects (small 
unicellular organisms, etc.) are fixed, washed and stained by suc¬ 
cessive quantities of fluid which are decanted off from the sediment 
of material, is objectionable, not only from its tediousness and 
difficulty of thorough washing, but also from the fact that it pro¬ 
hibits the use of the more delicate cytological stains. With these 
stains it is very generally necessary that a given fluid, after pro¬ 
ducing the right degree of differentiation, should be quickly and 
completely removed; such a rapid change of fluid is however im¬ 
possible by the decantation method. 
The difficulty in question could clearly be got over by fixing 
the objects to a slide in the manner of sections. For this purpose 
two methods have been devised, but both have considerable 
objections. One method is that of Overton (Zeit f. wiss. Mikrospie 
Bd. vii. 1890, p. 9), in which the objects, after being brought up 
to absolute alcohol (if necessary, by placing them in dilute alcohol 
