130 



THE AMEKICAN MONTHLY. 



[Jnly, 



The collector will not know the 

 value of his find until it has been 

 brought drop by drop under the lens 

 of his microscope, and out of the en- 

 tire mass he may discover nothing to 

 reward his labors ; this, however, 

 should not discourage him, as one or 

 two failures are to be expected prior 

 to meeting with an adequate reward. 

 His interest in the study will be 

 greatly enhanced if he keeps a record 

 of it in sketches of what the micro- 

 scope reveals to him. These sketches 

 should, of course, be very exact, and, 

 in order that they may be so, it is 

 necessary that the microscope should 

 be provided with an eye-piece mi- 

 crometer with which to measure the 

 length and breadth of the figure to be 

 sketched ; a half inch per^^L-fj- (.001") 

 or 31^ ^ is the most convenient, though 

 ^ or ^ of an inch may be a preferable 

 scale for the larger forms. It is so 

 difficult to separate specimens from 

 their accompanying foreign matter 

 that it is seldom amateurs can mount 

 them satisfactorily on slides, and 

 therefore this method of presei-ving 

 specimens is not open to recommen- 

 dation. 



Although in the microscopic study 

 of the fresh-Avater algas much has 

 been done within the past few years, 

 much more remains to be accom- 

 plished. The field, instead of grow- 

 ing smaller, seems to widen out 

 with every fresh discovery ; localities 

 thought to have been exhausted of 

 additional possibilities have, in sub- 

 sequent seasons, yielded ample re- 

 turns to the patient explorer ; and if 

 the old territory is not sufiiciently at- 

 tractive there are vast regions into 

 which no student has yet penetrated, 

 where, doubtless, the harvest await- 

 ing the reaper dwarfs all that has 

 been heretofore garnered. 



Fish Killed by Utriciilaria. 



[The following communication 

 from Mr. R. E. Earll, of the United 

 States Fish Commission, "w^ill prove 

 interesting to all who have aquaria in 



which small fishes are kept. We are 



surprised to learn, however, that the 

 facts mentioned have been so recently 

 observed. We are under the impres- 

 sion that the habits of the plant have 

 long been known, although unable at 

 present to find any account of its kill- 

 ing of young fishes. Perhaps some 

 botanist among our readers will be 

 able to refer to other observations of 

 a similar natui'e. — Ed.] 



Prof. Baird has just received from 

 Prof. H. N. Moseley, of Oxford Uni- 

 versity, England, a specimen of an 

 aquatic plant holding in its fond em- 

 brace a considerable number of young 

 fish which it had caught and killed. 



The plant is the well-known blad- 

 derwort, Utriciilaria vtdgaris L., 

 which is widely distributed over Eng- 

 land, and has been introduced into 

 our waters, ^vhere it is often found in 

 abundance in ponds and ditches, and 

 in the shoal-water coves along some 

 of our river-banks. It is a large 

 plant, with stems often attaining a 

 length of two or three feet. It has 

 no roots, but floats free in the water, 

 its root-like branches covered with 

 pinnatifid capillary leaves, each bear- 

 ing one or more small transparent, 

 hollow bladders, with openings at 

 one end, which serve as traps to catch 

 newly-hatched fishes, minute crusta- 

 ceans, worms, and infusoria. It has 

 no digestive apparatus, but is thought 

 to derive nutriment by absorption 

 from the decomposing animals. 



The bladder^vort has long been 

 known to catch the lower forms of 

 animal life, but it Avas only recently 

 that its fish-catching propensities -were 

 discovered. Mr. G. E. Simms, of 

 Oxford, was the first to call public 

 attention to the fact on finding that 

 a specimen w^hich had been placed 

 in his aquarium was actually catching 

 and killing large numbers of newly- 

 hatched perch and roach which had 

 hatched from a mass of eggs lying at 

 the bottom. The little fishes were 

 usually caught by the head, but some 

 were caught by the tail, while others 

 were doubly trapped, the head being 



