HARDWICKKS SCIENCE-GOSSIP. 



99 



Veronica Buxbaumii to chickweed, and then back to 

 Veronica. Bee No. 4 passed from celandine to 

 scilla. On another occasion : Bee No. 1 visits 

 Sowers in the following order : hyacinth, l'ero?iica 

 Buxbaumii, sweet violet, hyacinth, Veronica Bux- 

 baumii. Bee No. 2 goes from red dead-nettle to 

 hyacinth. The bee which has obtained the highest 

 place on my record behaved as follows : 



Geranium Robertianum . . 2 visits 



,, nemorum . . . 3 ,, 



„ Robert 3 „ 



,, lucidum .... I visit 



,, Robert 1 ,, 



„ lucidum . . . . 1 ,, 



,, Robert 6 visits 



,, sanguineum. . . I visit 



, , Robert .... 4 visits 



., nemorum . . . 2 ',, 



„ Robert 3 „ 



That is to say, 10 changes for 27 visits. 



On one occasion I watched some bees visiting 

 campanulas growing near a bush of syringa. During 

 a few minutes' observation, six bees passed from the 

 blue flowers of the former to the white flowers of the 

 latter. Presumably many of them also returned to 

 the blue, but I only watched their movements in the 

 one direction. 



These facts are not brought forward simply to 

 correct an error which in itself seems of little 

 importance : they have an important bearing on the 

 bee-selection theory. It may be said, indeed, that 

 the erroneous conception of the bee's strict constancy 

 forms one of the pillars upon which the superstructure 

 of that theory rests. Now it seems quite evident 

 that the facts here brought forward are sufficient to 

 deal a death-blow to the above theory of the bee's 

 selective action. If the bee of to-day passes freely, 

 in many cases, from one species to another, then, 

 surely, a fortiori, would the bee of bygone ages pass 

 freely from variety to variety : the result of its visits 

 would be to obliterate the incipient species by crossing 

 it with the parent stock and with other varieties. 



The necessity of this assumed constancy of the bee, 

 as a factor in the evolution of the flower by its 

 selection, is admitted by Mr. Grant Allen in the words 

 already quoted. If bees fly from flower to flower of 

 different species, they too will " not aid cross-fertilisa- 

 tion, but rather prevent it." When, however, the 

 species are incipient, that is to say mere varieties, the 

 result of the bees' action will be to blend them 

 together. 



We are sorry to see that Professor Williamson, 

 F.R.S., has retired from the Chair of Botany, at Owens 

 College, Manchester, after more^than half a century's 

 long, faithful, and enthusiastic services. Professor 

 Williamson was a bom teacher, capable of enlisting 

 hosts of recruits in botany, both recent and fossil. 



NOTES ON THE INFUSORIA. 



By Bernard Thomas. 



III. 



7- /^HsETOGLENA VOLVO CINE A (Fig. S3 

 v-^ f, g) is somewhat larger than the preceding, 

 as it is a little less than the thousandth of an inch 

 in its longest diameter. It is about twice as long as 

 broad. From the anterior part of the cell-wall there 

 is a projecting rim surrounding the hole through 

 which, as in ^Doxococcus, the flagellum protrudes. 

 The cell-wall is dark olive-green in colour and the 

 contained protoplasm resembles the previously de- 

 scribed species. There seem to be two varieties, both 

 similar in shape, but in one the cell-wall is rough 

 externally, in the other smooth. 



The forms Euglena, Phacus, Doxococcus, and 

 Chsetoglena belong most probably to the Alga?, and 

 are hence plants. Several of their near allies, 

 furnished with flagella, live in colonies, among which 

 we might mention Valvox, Gonium, Pandorina, and 

 several others. It is not here intended to enter into 

 a description of these forms, as they, even more 

 evidently, belong to the plant circle. Indeed the 

 preceding are only here introduced to contrast them 

 with the Flagellate Infusoria. We may briefly group 

 these relations as follows : — ■ 



A. Principal resemblances to the Infusoria (Flagel- 



lata). — Presence of flagellum in- all species. 

 Unicellularity. Contractile nature of ectosarc 

 in some species (e.g. Euglena viridis). Eye- 

 spot present in some Infusorians (Dinobryon). 



B. Principal differences from the Flagellata. — 



Presence of green chlorophyll. Presence of 

 eye-spot. Absence of food -vacuoles, and 

 perhaps of contractile vesicles. Nature and 

 manner of life. 



8. Cercomonas acuminata (Fig. 54 a) is usually 

 found in large numbers in putrifying pond-water. It 

 is exceedingly small, so small, indeed, that it requires 

 a high power with good definition to make out 

 anything of its structure. In its interior a few 

 granules can generally be distinguished. From two 

 opposite ends there arises a delicate process, one of 

 these is a flagellum but the other is described as a 

 delicate protoplasmic thread or tail, incapable of 

 vibration. 



This little organism is a representative of the 

 Monads, whose life-history has been so well worked 

 out by Drs. Dallinger and Drysdale ; and it was 

 then shown that these Monads reproduced not only 

 by fission but also sexually, by conjugation. 



The term Monad was at one time applied to all the 

 Flagellata. 



9. Anisonema (Fig. 54 b), which seems to be 

 identical with Bodo grandis, is an infusorian of con- 

 siderable size, larger even than Astasia. Besides the 



F a 



