June 29, 1883. J 



KNOWLEDGE ♦ 



383 



LONDON: FRIDAY, JUNE 2'J, K-^SS. 



Contents op No. 87. 



VAOS. P&OB. 



Fleuant H.urs with the Micro. , The Fisheries Exhibition. II. By 



scope. By H. J. Slmck. F.G.S. 3« J. E. .Wv 389 



The Beernt Solar Eclipse. Bv < The Moon in & Three-Inch Tele- 



R. A. Proctor '. 3S3 scope. (Illu..) Bv F.B.A.8. ... 390 



Oar Chemistry Column: The Halo- I Sun Views of Great Britain. {Illu.) 390 



cens. Bv W. Jago, F.C.S . 393 Editorial Gossip 391 



The Weather Forecasts of the Correspondence : Fliirht of Vertical 



Meteoroloeicil Office. Bj W. Missiles— Rational Dress— A Few 



Mattieu Williams ..., 3S3 ■ Obserrations on Heat, 4c 393 



The Birth and Growth of Myth. X. | Oar Mathematical Coltunn 397 



Bj Edward Clodd 357 I Oar Cheaa Column 397 



PLEASAIS^T HOURS WITH THE 

 MICROSCOPE. 



By Henry J. Slack, F.G.S., F.R.M.S. 



IN recognising different groups of infusoria, the most 

 obvious characteristics are afforded by their organs of 

 locomotion, or when they are stationary, by those for 

 seizing their food. Stein divided the ciliated kinds into 

 four groups, which he named Ilolotric/ia, all over cilia ; 

 lleterotrichn, having cilia and styles ; llypotricha, sliowing 

 a distinction between back and front sides, the latter only 

 ciliated ; I'eritricha, the body generally naked, but ciliated 

 near the mouth. It is not worth while for the beginner to 

 trouble himself much about principles of classification, but 

 the above names represent facts of great importance to the 

 little animals, and very interesting to observe. Specimens 

 of all these groups are to be seen in hay infusions, 

 and their modes of life present considerable variations. 

 The drawings of these objects in the best works 

 show all that can be seen under the most favour- 

 able circumstances, and all that has been seen after 

 prolonged study and numei^ous observations. At first 

 these representations bewilder the student, as many details, 

 quite plain in the drawing, are invisible in the objects 

 before him. For example, the star-shaped, contractile 

 vesicle of a parameciuni is difficult to discern while the 

 animal is actively moving, but easily recognised as it gets 

 quiet, and the water-drop dries up. The mouths of the 

 smaller creatures are often unnoticeable unless food par- 

 ticles are seen to enter, and the nucleus and nucleolus 

 (endoplast and endoplastule of Huxley), which probably 

 represent male and female organs — though this is disputed, 

 make a conspicuous show in the books, and often require 

 A good deal of management to see plainly in the living 

 objects. 



A little carmine in the water is of great use in finding 

 the mouth of an infusorian. The bright red particles are seen 

 to be swallowed, and their subsequent course can be traced. 

 When they are noticed in numerous groups, occupying 

 small clear spaces, the most obvious explanation is that the 

 creature possesses a plurality of stomachs, and hence 



Ehrenberg, the great founder of knowledge concerning 

 them, called them roly<jaslrica, or many - stomached. 

 Further observation showed that a stomach could be 

 formed when required in the soft sareode, and that even 

 wht>n there was a permanent gullet with thickened corru- 

 gations, no stomach existed, having a permanent place, and 

 its own bounding membranes. Externally a ciliated in- 

 fusorian has a skin, or pellicle, stiff enough to support its 

 swimming organs. In some cases this pellicle is highly 

 elastic, and permits great changes of shape, while in others 

 it is unyielding and the form fixed. Amongst the Ileti'.ro- 

 trirlia the integument is strong enough to permit the 

 bristles, or styles, to act with considerable leverage. They 

 may often be seen to have a bulb at their base, which 

 works in a thickened mass of tl e pellicle, so as to perforn^ 

 the function of a ball and socket joint, though it is a muc 

 simpler structure. 



Below the pellicle comes a layer of elastic sarcode froi 

 which the cilia spring. The internal part is composed' 

 protaplasm full of granules, and very soft. It is not . x- 

 commonto find protoplasm spoken of as homogeneous, I'Ut 

 there is no such thing. Granular matter is always pte- 

 sent, immersed in a transparent fluid. As .soon as one of 

 the ciliata has swallowed a food-particle, and transferred it 

 to its interior, the protoplasm forms a vacuole into which 

 it pours a digestive fiuid ; and when it has been suffi- 

 ciently acted upon, the waste matter is excreted either 

 through a permanent anus or through a temporary open- 

 ing which closes up. Many infusoria are supplied with 

 trichocists, or little cells, in the fiim protoplasm, from which 

 it can emit minute rods, or needles, supposed to act like 

 the stinging organs of polyps and anemones. Simpler 

 than the ciliated infusoria are the jlarjeUata, which swim 

 by means of one or more whips. 



Mr. Saville Kent, whose " Manual of the Infusoria " 

 is the greatest English work on the subject, and whose 

 opinion is entitled to much weight, proposes a new division 

 of the creatures, which we shall now describe, because it 

 suggests interesting points for the student to look for. He 

 includes under the name of infusoria only such protozoa, 

 or rudimentary animals, as are furnished in their adult 

 condition with cilia, tiagella, or adhesive, or suctorial 

 tentacles, and which take in their food by one or 

 more distinct apertures, or at any part of their 

 bodies. Minute animals, moving with whips, fill his 

 section of Pantostomata, or universal mouth creatures ; 

 then come his Discoslomnta, which have whips, take 

 in their food at some point in a definite anterior 

 region, but have no mouth. After this comes Eustomala, 

 well-mouthed, in which a distinct mouth exists ; and 

 lastly, rolystomata, or many-mouthed, which include 

 creatures with tentacles by which they suck the contents 

 out of their prey, or obtain it by first pouring some of 

 their own fluid matter into the prey, and then setting up a 

 current which brings it Viack laden with fresh matter. 



The two systems of classification, one founded upon 

 locomotive organs, and the other upon mouth organs, both 

 suggest what the student should look for. The modes of 

 reproduction should also be noticed. The commonest 

 is by fission, either transverse or longitudinal. It is ex- 

 tremely interesting to see a creature split itself into two. 

 Before the separation occurs, an internal growth takes 

 place, so that each half departs fully organised. This 

 method allows an amazingly rapid multiplication, so that 

 Ehrenberg computed that a single Styloiiichia mytihts 

 might have a million descendants in ten days. Many of 

 the small flagellata, or whip animalcules, form sporocysts, 

 or capsules of spores. Mr. Dallinger found some of these 

 spores too minute for individual recognition with a power 



