June 1, 1886.] 



KNOWLEDGE 



247 



also injudicious not to indicate the amount of magnification 

 in each case. 



Amongst the rotifers with comparatively simple mouth- 

 oi'gaiis those belonging to the Asplaiichna, or bowelless 

 species, are of great interest, as their perfect transparency 

 makes it e;i.sy to work with both high and low powers. The 

 biting machine of Asplatichna is like a pair of young deer's 

 antlers, with sharp projections. It is a nipper, not a 

 giinder, and often lets swarms of live objects through with- 

 out noticeably injuring them. The voracity of the creatures 

 is amazing, and the present writer supplied some curious 

 illustrations of this in the " Intellectual Observer" (vol. v. 

 p. 182). In the stomach of one Asplancli iia were seven 

 small rotifers, the jaws of an eighth, one arcella, a quantity 

 of imperfect crystals, perhaps uiic, together with a mass 

 of matter sufficiently digested to conceal its origin. The 

 stomach of these creatures is very elastic, and is not incon- 

 venienced by large hard objects that force it quite out of 

 shape. When it is tii'ed of them they ai'e pitched out by the 

 way they came in, together with other indigestible debris. 



An exceedingly voracious animal, which bolts its food at 

 a rapid rate, evidently throws hard work upon its stomach. 

 If we have to stew a mass of matter quickly into a 

 soft pulp, we stir it well about in hot water. The 

 Asplanchna is not provided with a spoon for this purpose, 

 but its stomach is lined with active cilia, and they force 

 currents of the digestive fluid in all directions amongst the 

 objects to be acted upon. The direction of these currents 

 fluctuates as the resistance gives way, and the sight is a 

 fine one with powers of from 500 to 1,000 diameters. 

 Fig. i is from a sketch made by Mrs. Slack under the 



fv X 





M 

 m 



m V 



t 1 ^"'jj'l/,U'i''0'> 



:^h' 







Fig. 4. 



latter magnification. It would be an interesting task to 

 examine a variety of rotifers and see in what cases stomach 

 currents were employed as important aids to digestion. 



The aspect of the mastax of many rotifers as seen in one 

 position when the creatures are alive is apt to mislead 

 the observer in imagining a form they do not possess. The 

 organ should be viewed in all directions, both while it is in 

 the animal and after the whole of the soft parts have been 

 removed by solution of cau.stic potash. Mr. Gosse frequently 

 found it necessary to cause the apparatus to turn over, which 

 can be done by using the screw of a compressorium and 

 making wavelets in a water-drop holding the object. 



With every wish to recognise and welcome " The Itoti- 

 fera," and to give due credit to Dr. Hudson, we cannot help 

 wishing Mr. Gosse had been able to take a larger share in 

 the new work, which would then have been free from the 

 blemishes pointed out. The third part, lately out, describes 

 and figures many of the most interesting genera, including 

 Asplanchna. The three parts are intended for one volume, 

 but we imagine most purchasers will consider it too thin 

 and bind all together when complete. 



THE NATURALIST'S LABORATORY. 



COXTRIBITION I. 



URING the past few years the rapid progress 

 of natural histor\-, which has marked our 

 era as pre-eminently the scientific age, may 

 be claimed with justice to have resulted 

 chiefly through the importance attached 

 to practical laboratoiy work. All our 

 most eminent teachers are agreed that 

 a sound scientific training must be a permanent educative 

 process ; that a true knowledge of the forms and functions 

 of living things, as well as of inert matter, can no longer 

 be regarded as attainable through pure speculation, or any- 

 thing which savours of things metaphysical, as it was in 

 mediiBval times, but must be sought for by each worker 

 through diligent observation and experiment. A sound 

 preliminary training, adapted to lead the student to futuie 

 original re.'-earch, is thus reduced to one of actual practice. 

 His first step must necessarily be one of verification ; he 

 should not take for gi-anted that what previous workers 

 have stated is absolutely true, but endeavour to ascertain 

 b)' exj^eriment the actual worth of their records ; for, in the 

 majority of instances, personal errors play an important 

 part, so that when researches are published it would be of 

 great value to future investigators if the authors would 

 always note the precise plans followed in attaining results 

 from which they deduce their conclusions. To a neglect of 

 this duty may be traced much of the aimless disputes which 

 characterise the terminations of many so-called learned 

 societies' proceedings ; whereas, its observance would aflord 

 a ready means to other workers for tlie correction of indi- 

 vidual errors and the advancement of truth. Such a plan, 

 if universally followed, would also enrich the laboratory 

 immeasurably, for every original paper would contain notes 

 of some instrument, some receipt, or some novel method of 

 value to be added to its stores. 



The naturalist's laboratory of to-day is very prone to 

 degenerate into a kind of lumber-room, because of the want 

 of definite information in a compact form, to meet the re- 

 quirements of the present day. The principal aim of the 

 series of contributions of which this is the first, is to supply 

 a systematic compilation of notes for the guidance of both 

 private and jjublic students, to enable them to derive the 

 benefit of all the most valuable results of former workers, 

 both ancient and modern, to the utmost, and thus to facili- 

 tate research. 



Until recently the term naturalist was applied more 

 exclusively to certain lovers of the beauties of nature, who 

 prided themselves upon studying the general habits of plants 

 and animals, making collections of their dead remains, and 

 naming them after separate fonciful codes. The naturalist's 

 laboratory of the time of White of Selborne, or even of 

 the late 8ir William Jardine, wore more the aspect of a 

 kind of old curiosity shop than of a scientific worker's 

 sanchun ; where bii'ds' skins, dried plants, cured insects, 

 shells of molluscs, and fossils were carefully stowed away in 

 drawers redolent with camphorated essences, &c. The 

 mania for merely collecting and arranging was not then 

 confined, as it is now, to what are aptly called " scientific 

 amateurs," but was followed more or less by all the leading 

 men of the day, from Linnwus downwards. It has at length 

 been fortunately developed in the right direction, and public 

 depositories in the form of museumsof science and art have been 

 widely instituted. Here the storage of birds' skins and dried 

 plants assumes its noniial place ; they are of specific value 

 to the general taxonomist, and, when CiU-efully prepared, 

 are second only to elaborate and accurate woiks of pictorial 

 art. 



