176 



HARDWICKE'S SCIENCE-GOSSIP. 



may now be seen vibrating somewhere near the 

 centre of the organism. When the stalk begins to 

 unwind, the disc and peristome come slowly out. If 

 while the bell is opening it come into contact with 

 any obstacle, it immediately closes again. There is 

 another movement which takes place when the bell 

 closes, and this is the contraction of the cone-shaped 

 portion of protoplasm which unites the bell to the 

 stalk, and here, as was mentioned, we usually see 

 myophan striae. 



3. The stalk consists of a cuticular sheath, con- 

 taining a delicate, finely granular thread of proto- 

 plasm. When the thread shortens, 'the sheath is 

 thrown into a close spiral. Contraction is usually 

 effected very quickly, but expansion more slowly. 

 The protoplasm inside the sheath has been called a 

 muscle, and although, of course, it has no muscular 

 structure (properly so called), it is muscular in 

 function and so also are the other essentially con- 

 tractile portions of the protoplasm, which move the 

 disc and peristome. Perhaps we may look upon 

 these "muscular" portions of protoplasm as due to a 

 collection of the more specially contractile elements 

 in these regions. 



4. The internal movements are similar to those 

 seen in other Ciliata. There is a single large 

 contractile space. In a sessile species the interval 

 from systole to systole was thirty-two seconds, and 

 it may be mentioned that a strong furrow was pro- 

 duced in the ectosarc when this organ contracted. 

 The mouth leads into a short, non-ciliated 

 oesophagus, which ends blindly in the pro- 

 toplasm. Particles drawn into the gullet, 

 sink into the endosarc, and there form food 

 vacuoles. In short, the same description 

 applies to Vorticella as to Parameceum. 

 Vorticella as well as other Infusorians be- 

 comes encysted (Fig. 112, d). The bell 

 closes and a firm cell-wall is secreted. These 

 encysted bells are free from their stalks, and 

 may be found as little balls of protoplasm, 

 surrounded by a firm cell-wall. A repro- 

 ductive process by division of the nucleus has 

 been described in connection with encysta- 

 tion. 



Reproduction is, however, most commonly 

 effected by fission. In this case the division 

 takes place longitudinally (Fig. 112, a). 

 When two bells are thus produced, one of 

 them develops a ring of cilia at the base. 

 The cilia are seen springing from a con- 

 striction as small processes. As time advances 

 the basal cilia become stronger and more distinct. 

 Apparently from their first appearance they are 

 vibrating. The new Vorticella furnished with these 

 extra cilia now swims freely about until it finds a 

 spot to fix itself (Fig. 112, b). 



These basal cilia may be produced in a Vorticella 

 that has not divided (Fig. 112, c). Another method 



of reproduction, in which a small, free-swimming 

 Vorticella (the male) attaches itself to a fixed form 

 (the female), is described as sexual. As a result of 

 the fusion of these and of their nuclei, other smaller 

 individuals are produced. 



There are other representatives of this genus, 

 among which may be mentioned : 



31. Vorticella chlorostignia, whose bell contains 

 chlorophyll. 



32. Vorticella microstomum, a small and fairly 

 common species. 



THE MYMARID^:. 



AS I do not remember to have seen the family 

 of "Fairy-flies" noticed in your columns, I 

 venture to trouble you with this paper, hoping that 

 the subject may attract the attention of abler 

 naturalists than I can claim to be, and lead those of 

 your readers who can boast no higher degree than 

 that of S.G., or "Science Gossip," to many hours 

 of delightful investigation. 



The very existence of these tiny beauties, who, 

 however, are our most constant companions in the 

 summer months, is unknown to many who will be 

 delighted to make their acquaintance ; so I will at 

 once proceed to introduction by telling them how 

 to discover and catch them, which will at the same 

 time explain something of their nature and habits. 



Well, then, being armed with a pair of good 



Fig. 1 



13. — Fairy Fly. Nat. order, Hymenoptera ; family, Mymaridae; 

 genus, Anaphes, £. From "Nature" (not Macmillan's). 



eyes, or a pair of good " specs.," as your age or youth 

 may determine, a very small white wide-mouthed 

 phial containing a teaspoonful of pure turpentine 

 or oil of cloves in your left hand, and a light 

 pen-holder or stick) terminating with half an inch 

 of a coarse hair or fine bristle, proceed to examine 

 the panes of a sunny window, the lower sash of 

 which is partly open, and if a gentle wind be 



