HARDWICKE'S SCIENCE-GOSSIP. 



i8i 



The foot seems very flexible indeed ; I have seen 

 it preen itself round the head with it hke a bird does 

 its feathers with its bill. The toes too it can arch, 

 the points touching, and a wide space being between. 

 In the one drawn the foot seems shorter and thicker 

 than usual ; it was very quiet, and possibly may have 

 been of a retiring disposition, wishing to keep itself 

 to itself, or perhaps pulling itself together for a fresh 

 start in life. I have not seen it lengthen and shorten 

 its foot with the double telescopic power possessed 

 by many rotifers. In colour it is of a pearly grey 

 hue, with two red eyes. The shield turns round the 

 head somewhat like a collar, and the edge, looking 

 down on it, appears like a bristle. 



No. 3. — OllCrSTES UMBELLA. 



This beautiful rotifer was discovered in 1878 at 

 Snaresbrook. It has since been found at Sutton 

 Park, Birmingham, at Woolston, Cheltenham, also 

 at Perth and Fife. In length j'^th inch, it can be 

 easily seen with the naked eye. I have found it in 

 some abundance on Tooting Common in a shallow 

 pool, from which I have taken some of the rarest 

 rotifers, including CEcistes velatus, Notops hyptopus, 

 Copeus labiatus, and a new stephanops. 



CEcistes mnbella lives on the leaves of myriophyllum, 

 in a very transparent mass of gelatinous material, 

 forming an irregular case of a yellowish tint, and 

 which does not seem to be of an adhesive nature, on 

 account of which a good view can be had of the 

 entire animal. 



In Figure No. 120 the foot is in a contracted state ; 

 when elongated it would be at least double the length 

 shown. The chief characteristic of this species is the 

 circular corona, strengthened with radiating ribs, and 

 surrounded with long cilia. It must not be thought 

 that this leads down like a funnel to the mouth ; it is 

 almost a disk when fully expanded, without any 

 opening in the centre. 



The buccal cavity, Fig. 119, 2, is just under the 

 corona, running transversely across the animal, open- 

 ing between and above the ventral antenna. The 

 second row of cilia is beneath the corona, forming a 

 channel, along which the food is carried ; this ciliary 

 wreath then runs down round the margin of the 

 buccal funnel, which thus opens between the two 

 wreaths. The food is drawn down by the whirlpool, 

 formed by the cilia on the margin of the disk, and is 

 immediately turned over its edge into the gutter 

 formed by the second wreath, and conveyed with 

 great rapidity to the buccal cavity. It there im- 

 pinges on a sensitive cushion, and is divided into two 

 portions ; one passes on to the mastax to be swallowed 

 as good food, the other to be forcibly ejected as refuse. 

 The attractive force of the current created by the 

 cilia of the margin must be great, as I have seen a 

 large volvox, at some distance, drawn on to the disk, 

 and driven round on it with great velocity, this novel 



cup and ball forming a lovely object. I have also 

 seen a rotifer niacrurus treated in the same way. 



The (X'sophagus is plainly seen, as a curved tube, 

 opening into the back of the stomach. The intestine 

 bends upward, and terminates at a slight enlargement, 

 only a little below the level of the antennas, but on 

 the opposite side of the animal. The contents are 

 thus, when expelled, driven upwards, and out of the 

 tube the animal lives in. The eggs are long, and 

 dark in colour. 



Under a low power the animal, in a contracted 

 state, may be recognised by an orange stain in the 

 region of the mastax, and by the ribs of the large 

 folded corona. As this expands, it is first pushed 

 forward, and appears as a dark grey cone. The ribs 

 open like an umbrella, the membrane being regularly 

 folded between them, as in that useful incumbrance, 

 whence the species takes the name " umbella." 



THE DEVELOPMENT OF THE COLOURS 

 OF FLOWERS THROUGH INSECT- 

 SELECTION. 



\Contiiiited from p. 162.] 



THEX, as to Mr. Robertson's "three alterna- 

 tives," I have shown that it is absurd to 

 assume that the first ought to have happened ; one 

 might as reasonably argue that all low forms of 

 animal and plant life ought to have been eliminated 

 long ago. As to the other two alternatives, the 

 second is true in the main, and Mr. Robertson's 

 description of what would happen in that case is 

 strikingly like what has actually taken place ; but 

 some short-tongued bees have been little altered as 

 regards the length of their tongues. (I may ask, in 

 passing, why the evolution of long-tongued insects 

 should be considered a "disturbance of Nature's 

 scheme"?) I do not see why we "might reason- 

 ably expect to find a much larger proportion of 

 specialised .... flowers than are actually to be 

 found " ; we might as well argue that we ought to 

 find a larger proportion of specialised animals than 

 are found, on the ground that the general process of 

 natural selection and other means of specialisation 

 have been in operation since the first appearance of 

 life. According to Mr. Robertson, short-tongued 

 insects " probably .... far outnumber the long- 

 tongued," and it is for these that the unspecialised 

 flowers are adapted. There will always be room for 

 primitive organic forms, and moreover there is plenty 

 of time for further specialisation in the future. The 

 same general argument applies to the objection that 

 more species of bees ought to be specially adapted to> 

 particular species of flowers : and further it must 

 be remembered that excessive sjjecialisation in this 

 direction has serious drawbacks ; for suppose the 

 flowers of one of these species were very scarce for a 



