1880.] 



MICROSCOPICAL JOURNAL. 



193 



of evolution has transfonned them 

 on the leaves into those wonderful 

 motile amis adapted to the capture 

 of insects, but has left them un- 

 chan2:ed on the tlower, where that 

 function would be of no use to the 

 plant. I occasionally find in my 

 preparations a solitary mushroom 

 gland among the tentacles of the 

 leaf — a remnant of a race that has 

 been supplanted. There is found 

 in Portugal a plant very similar to 

 the Drosera, the Drosophyllum, 

 which has still only the nmshroom 

 glands on its leaves, and catches in- 

 sects in great quantity by loading 

 them down with the viscid secretion 

 which these glands abundantly pour 

 forth. 



To exhibit the very delicate 

 structure of the leaf and tentacles of 

 the Drosera, it is necessary to color 

 them but slightly. The danger will 

 be in over-staining ; therefore, after 

 decolorizing and immersing for a 

 few hours in the carmine solution, 

 the specimens sliould be exposed to 

 only a very weak fresh solution of 

 logwood for fifteen or twenty min- 

 utes. If the anilin blue is resorted 

 to at all, it must be in a very weak 

 solution. A mounting of a leaf and 

 a stem with flower buds in one cell 

 in camphorated or carbolated water, 

 makes a very pretty and complete 

 slide for the Drosera. 



The LTtricularia is a floating, car- 

 nivorous plant which grows in the 

 shallow water of quiet ponds. On 

 the surface of the water from Ave to 

 seven leaves are spread out like the 

 spokes of a wheel, and from the 

 centre of these leaves the plant 

 sends upward its flower stalk and 

 'downward its root-like branches, 

 floating freely in the water. 

 Among the thickly branching fibres 

 of these long submerged stems, are 

 perched innumerable little bladders 

 or utricles, not much larger than the 

 head of a pin, each provided witli a 



moutli, at the bottom of a sort of 

 funnel of bristles, closed with a 

 cunning little trap-lid which opens 

 inward, engulfing and imprisoning 

 whatever minute creatures or sub- 

 stances may happen to be resting on 

 it. In these sacks during the grow- 

 ing season, we will find numerous 

 microscopic water fleas, mites and 

 beetles, with grains of pine pollen 

 and other floating particles. The 

 organic bodies will be found in all 

 stages of digestion, showing that the 

 plant derives nourishment from such 

 captured prey; and apparently its 

 only means of livelihood is trapping. 



When taken from the water and 

 dried under slight pressure, the 

 submerged portions of the Utricu- 

 laria will be found literary covered 

 with diatoms ; and many very inter- 

 esting chrysalids of water-insects 

 will be found attached to them. 

 These will all be washed off if the 

 plant is bleached in chlorinated soda. 

 To preserve them it will be neces- 

 sary to remove the color in alcohol, 

 and besides to handle very carefully. 

 The staining can only be single ; and 

 I have found a weak solution of 

 eosin in water, to be the best 

 material for coloring, showing at 

 the same time the structure of 

 the utricles and the captures con- 

 tained in them. Specimens of new 

 growths, showing the just forming 

 utricles and the peculiar circinate 

 mode of growth, should be included 

 on the slide. The mounting should 

 be in camphorated water. 



The Pinguicula, another of the 

 insectivorous plants, is found abun- 

 dantly on the more open plains, and 

 not far from wet places. It is a 

 compact rosette of very light green 

 leaves, growing close to the ground, 

 from the centre of which rises a 

 single flower-stalk, eight or ten inches 

 high. The leaves have their edges 

 turned up, f oi-ming a shallow trough, 

 and on the upper surface are mush- 



