1 66 



NATURE 



\yunc 24, 1880 



so did the knowledge of these forms increase. Ehren- 

 berg and Dujardin led the way to a brilhant series of 

 discoveries, wliich have been continuous, and never more 

 numerous than during the last twenty years. 



One protozoon was on the roll-call of the sy sterna natiircE 

 — who could count the vast multitude known to us now ? 

 The very list of the provisionary classes and sub-classes 

 would be a long one. 



On so!ne of these classes splendid monographs have 

 been written, among which those of Stein, Carpenter, 

 Claparede, Haeckel, Wallich, and Brady may be men- 

 tioned, while the authors of papers on special genera and 

 species would be too numerous to quote. 



Most of the authors referred to have worked among the 

 European forms, but Carter added greatly to our know- 

 ledge of those to be met with in the Island of Bombay. 

 Africa and America were unknown countries ; while the 

 former still remains so, the persevering efforts of Dr. 

 Joseph Leidy for the last ten years have gradually un- 

 folded to us the rhizopodal wealth of North America, 

 and have culminated in the publication of the finely- 

 illustrated work that we proceed to notice. 



As preliminary we are reminded that there is no very 

 fixed system of classification for this class. Dr. Leidy 

 treats of the fresh-water species only, as found in the 

 orders Protoplasta, Heliozoa, and Foraminifera, the first 

 two being commonly designated " Freshwater Rhizo- 

 pods." These, writes Dr. Leidy, are to be found almost 

 everywhere in damp or wet, but not over shaded positions; 

 they are especially frequent and abundant in compara- 

 tively quiet waters, which are neither too cold nor yet too 

 much heated by the sun. They are to be found among 

 moss in spongy places or on damp rocks. They hide away 

 among sphagnum-leaves, at the roots of sedges and 

 grasses on the bark of trees. Once, we remember, Dr. 

 Leidy got quite a store of them in the fork of an old apple- 

 tree. Sometimes a depression or fissure in a rock, some- 

 times even the crevice of a wall or of the pavement, affords 

 them space enough. We have taken them almost at the 

 equator. Dr. Wallich has described many from within 

 the Arctic circle. The favourite habitation of many 

 forms is the light superficial ooze at the bottom of still 

 waters. If this be gently collected, there they will be 

 found grazing among the desmids and diatoms fond of 

 such quarters. The dark deep mud that will be found 

 below this it is as well not to stir ; it is a ]a5-er in which 

 life turns to death, and its odour is never pleasant. But 

 again, these rhizopods arc to be found in that creamy, 

 flocculent matter that half floats on the surface of great 

 pools. The expert collector will soon get to know the 

 difference in these " creams " — some so rich in treasures, 

 some containing nothing but dead cells and empty lorica ; 

 then again Dr. Leidy found these rhizopods in no place in 

 such profusion, number, and beauty of form as in sphagnous 

 bogs, living in the moist or wet bog moss {Sphagnum). 

 " Sometimes he found this moss actually to swarm with 

 multitudes of these creatures of the most extraordinary 

 kinds and in the most highly-developed condition. A 

 drop of water squeezed from a little pinch of bog moss 

 has often yielded scores of half a dozen genera and a 

 greater number of species." " Frequently, however," he 

 adds, " ihe sphagnum of many localities contains compara- 

 tively few rhizopods, though I have rarely found them 



entirely absent from the moss." In Ireland the very 

 reverse of this seems to ^hold true, and the exceptional 

 multitudes have not yet turned up. 



Dr. Leidy's volume is issued under the modest title of 

 a '■ Report," so that it seems desirable to mention that it 

 forms a large quarto volume of 324 pages, illustrated with 

 48 coloured plates. The printing and paper of the 

 volume are simply perfection, like, indeed, most of the 

 work issued from the Government printing-office at 

 Washington, and brought out under the superintendence 

 of Dr. F. V. Hayden. It forms one of the volumes of the 

 L^nited States Geological Survey, and its publication 

 betokens an enlightened zeal on the part of the United 

 States geologist in charge. As to the illustrations, we 

 think the author quite unduly hard in his estimate of 

 them. He says: "The illustrations accompanying this 

 work, done in chromolithography, are not equal in execu- 

 tion to my desire," and he regrets the absence from the 

 States " of those accomplished artists from Germany and 

 France." To our mind, as chromolithographs, the illus- 

 trations are excellent. The drawings are recognisable at 

 a glance. The slight hardness in outline and sharpness 

 of colouring are not defects to be made over much of, 

 and we feel sure that these plates will be for the most 

 part recognised as good and excellent representations of 

 the forms described. 



There are about seventy-five species, including those 

 of all orders, specially described in this volume, and it is 

 a pleasure to note how few new genera are proposed. 

 Speaking in general terms, Prof. Leidy seems to believe 

 in there being a very large range of variability in the 

 species, but it is not improbable that a more lengthened 

 study of the forms might considerably modify his views. 

 Any discussion on such points would be out of place in 

 the present notice. A controversy as to what is a species, 

 what a variety, would seem captious over a book quite 

 full of the facts in nature as Dr. Leidy found them, and 

 from which he leaves one in full confidence to draw their 

 own opinion. 



One very lovely form to this only known from North 

 America is called by Dr. Leidy Hyalosphcnia papilio. It 

 is doubly interesting as marking an era in its describer's 

 life. It is common and at times exceedingly abundant in 

 moist bog or sphagnum, or sphagnous swamps, but it is 

 not found in ponds unless accidentally. " No other lobose 

 rhizopod has more impressed me with its beauty than 

 this one. From its delicacy and transparency, its bright 

 colour and form as it moves among the leaves of sphagnum, 

 desmids, and diatoms, I have associated it with the idea 

 of a butterfly ho\ering among flowers. From its com- 

 parative abundance, the readiness and certainty with 

 which it may be obtained and observed, and from its 

 transparency, which allows its structure to be well seen, 

 it is peculiarly well adapted for the study of the life- 

 history of its order ; I have collected it from early spring 

 to late autumn, and have retained it alive in sphagnum in 

 a glass case in winter. This interesting rhizopod, found 

 together with a profusion of other remarkable microscopic 

 forms of both animal and vegetable life, of which many 

 are novel and yet undescribed, recalls pleasing recollec- 

 tions of excursions into the sphagnous bogs, cedar swamps, 

 and pine barrens in the southern region of New Jersey. 

 These localities have special charms for the botanical 



