HARD WICKE'S SCIENCE- G OS SIP. 



269 



and several contracting vesicles are generally visible. 

 The sarcode, in all my specimens, is colourless, and 

 the pseudopodia, which are never numerous, are 

 protruded in short threads radiating from the mouth. 

 In moving about, the shell is tilted back from the 

 perpendicular, owing to the position of the mouth. 

 No testaceous Rhizopod is more variable in size than 

 Trinema ; I have seen specimens as small as the ji,^^ of 

 an inch in length, and the sphagnous forms may 



Fig. 219. — Trine- 

 }na acinus. Side 

 view. 



Fig. 220. — Ditto, 

 somewhat tilted. 



Fig. 221. — Front 

 view, showing 

 rounded mouth. 



Fig. 222. — Specimen of more 

 robust form of ditto. 



Fig. 223. — Side view 

 of empty test. 



reach jlg of an inch : but about 355 or -^^^^ of an inch 

 may be considered as average-sized specimens. 



Fig. 219. Side view of Trinema, showing oblique 

 mouth, contracting vesicle, pseudopodia extended. 

 From a well among Algse. 



Fig. 220. Another lateral view somewhat tilted. 

 From a well, &c. 



Fig. 221. Front view, showing rounded sub- 

 terminal mouth. 



Fig. 222. Front view of a more robust specimen 

 from Sphagnum, showing delicate punctations. 



Fig. 223. Side view of empty test, showing the 

 inversion of the mouth. 



This article is the concluding one as regards the 

 Rhizopods of the order Protoplasta, sub-orders Lobosa 

 and Filosa. In my next I propose to describe two or 

 three forms belonging to the order Heliozoa, which 

 differ in many material points from those previously 

 described. 



J. E. Lord. 



Rawtenstall. 



NOTES ON AN INSECTIVOROUS PLANT. 



ALL the plants of the genus Utricularia are 

 rendered highly interesting on account of their 

 peculiarly-constructed bladders. The greater bladder- 

 wort ( Utricularia vulgaris), one of the commonest, but 

 not the less interesting of the genus is frequently met 

 with in this country, inhabiting ponds, stagnant 



pools, and foul ditches. It floats near the surface of 

 the water, and is entirely destitute of roots. The 

 leaves are finely dissected into capillary segments, 

 and furnished with small bladders usually measuring 

 about one-fifth of an inch in diameter. The lower, or 

 under side of the bladder is nearly straight, and the 

 outline of the upper part rounded and terminating on 

 the outside with several antenna-like prolongations. 

 Thus the whole bladder in appearance bears a 

 striking resemblance to the "water-flea." The 

 bladder is fonned of two layers or cells ; the outer 

 layer consists of large polygonal cells containing water, 

 protoplasm, and chlorophyll, and between these much 

 smaller cells are formed also containing protoplasm. 

 The cells of the inner layer are round, and are 

 also accompanied with smaller cells which support 

 four short pyramidal processes terminating in two 

 large rounded cells — sometimes inclined to be 

 elliptical in outline. The transparent and elastic 

 valve or lid, composed of two minute layers of cells 

 continuous with two layers of larger cells, extends 

 nearly to the opposite side of the bladder, and is then 

 folded under, and rests, or rather presses against the 

 collar or peristome. The surface of the valve is 

 furnished with glands, and on the inner side of the 

 collar numerous small bifid processes are crowded 

 together. Both the valve and the collar proceed 

 into the cavity of the bladder, the entire surface of 

 which is studded with quadrifid processes. Animals 

 gain ingress to the bladder by pressing against the 

 free edge of the valve, which being highly elastic 

 shuts again immediately, and thus prevents their 

 escape. From the peculiar structure of the bladders 

 it may be inferred that they are specially adapted 

 for the capture of minute animals. They have been 

 supposed by some naturalists to be air-bladders by 

 means of which the plant is effectually floated in the 

 water, but having cut off all the bladders from 

 several branches, I found the branches to float as 

 well without them as those with them. I have also 

 found several branches destitute of bladders, and 

 they floated well, the only marked difference being 

 that the plant was decidedly weaker than those 

 possessing them. The amount of organic matter 

 held in solution within the cavities of the bladders is 

 considerable — for they are nearly always found to 

 contain a greater or less number of minute animals, 

 which ultimately become asphyxiated ; disintegration 

 then follows, and absorption begins, for the minute 

 processes — which may be considered analogous to 

 root-hairs — when microscopically examined show 

 their contents to consist of irregularly-shaped masses 

 of matter containing protoplasm. I placed several 

 plants in bell-jars ; some were kept in comparatively 

 pure water — the water being changed at frequent 

 periods — while others were kept in water literally 

 teeming with infusoria ; the plants kept in the latter 

 condition were not only of a darker colour, but of a 

 more vigorous growth, and the quadrifid processes 



