i8o 



NATURE 



{Dec. 28, 1876 



The visits to the flowers with partially apparent honey 

 a-\- b steadily diminishes from the Tenthredos to Andrena 

 and Halictus, but so that the diminution of the visits 

 entirely refers to the flowers with the honey apparent, 

 while, on the contrary, the flowers with honey partially 

 hidden are visited with still greater frequency. 



In the case of some solitary bees, the disinclination to 

 flowers with the honey apparent has reached to their total 

 abandonment. 



The transition to social life brings the development in 

 the second group, of which we have been treating, to an 

 end, as, in proportion as the number of individuals in a 

 community increases, the necessity for food forces them 

 to seek honey where they can, and it is indeed touching to 

 see the unwearied diligence with which the hive-bee will 

 collect almost imperceptible drops of honey from even the 

 smallest flowers. 



The perfection which the family of bees, viewed as a 

 whole, has attained, beginning with Prosopis, and rising 

 to the most perfect of the solitary bees belonging to the 

 group which collect pollen on their hind legs, consist : — 



1. In the increasing development of the pollen-bearing 

 apparatus. 



2. In the prolongation of the lower part of the mouth. 



3. In the increasing size of the individuals. 



The first is seen best in the humble and hive-bees ; the 

 third is very marked in the humble-bee, while the length 

 of the proboscis reaches its furthest point in Anthophora. 

 The hive-bee has a more perfect pollen apparatus than 

 the humble-bee, but is inferior to the latter in size and 

 length of proboscis, and only succeeds in obtaining more 

 honey through its more populous communities. 



It is well known that as a rule every hive-bee occupied 

 in seeking food from flowers specially devotes itself to a 

 particular species, passing by others, however rich in 

 pollen or honey. The advantages of this arrangement 

 are obvious, much fewer visits being made in vain to 

 flowers already plundered, and much greater dexterity 

 being attained in the case of flowers with complex forms. 



Two questions remain to be decided — 



1. Does each individual bee collect pollen and honey 

 from a single plant only (to which it has become adapted 

 by instinct, i.e., by inherited custom) 1 



2. Does the hive-bee possess a greater degree of intel- 

 ligence in deciding among the difl"erent species of plants 

 than the humble-bee and other lower forms 1 



The first question must be met with a decided nega- 

 tive ; tke second, as far as observation has yet gone, can- 

 not be answered with certainty. It would scarcely be of 

 advantage to the bee-community, whose object is the ex- 

 ploitation of as many flowers as possible, if its instincts 

 as to special tribes were hereditary. 



It is, on the contrary, to be observed in the hive-bee 

 that each bee makes vari«us essays before deciding on 

 any special tribe of flowers. For example, we have seen 

 a hive-bee in vain attempt to obtain the honey of Iris 

 psendacorus, and then fly to Ranunadus acris, which it 

 sucked at for some time. Another more than once bored 

 through the spur of Orchis laii/olia, loading its head with 

 two little clubs of pollen, and then flying to the flowers 

 of Lychnis Jioscuculi. 



A third, wandering over a field full of weeds, visited 

 one after another Veronica hedercefolia, Lithospermum 

 arvense, Sisyinbrium thalictrinn, and Viola tricolor. 



These and similar facts show that there can be no 

 question of inherited preferences for certain plants in 

 mdividual bees, and that the fact of each bee being de- 

 voted to certain plants is only to be ascribed to the sub- 

 ordmation of the interests of the individual to that of 

 the state. The humble-bee approaches the hive-bee in 

 the peculiarity of keeping to certain species, as weU as 

 m the number and keeping of its community. However, 

 though chiefly confining itself to the plants accessible to 

 It alone, as for example, Lamium album, &c., there are 1 



fairly numerous cases in which the humble-bee goes to 

 • other plants, and its baskets are often found full of very 

 varied kinds of pollen. 



Even in solitary bees, the special preference for special 

 kinds of flowers is a frequent habit. For example, An- 

 drena hattorjiana is found on Scabiosa arvensis, Cilissa 

 inelanura on Lytliruni salicaria, &c. ; but this prefer- 

 ence evinced by some solitary bees for a single species 

 of flower sufficing all their needs is radically different 

 from the practised and exhaustive pillage of all flowers 

 by a bee community, in which special individuals are 

 told off to gain the produce, however small, of special 

 families of plants. At first I believed I could answer the 

 other question propounded above, i.e., whether the hive- 

 bee promises a higher degree of intelligence in distin- 

 guishing different genera of plants than the humming- 

 bee and other lower forms, in the affirmative, on the 

 ground of the following observations : — In a field grown 

 over with weeds I saw one of our more intelligent humble- 

 bees, Bonibns agrorum, visit without distinction the little 

 whitish flowers of Viola tricolor var. arvensis, and those 

 of Lithospermum arvense, the same size and colour, but 

 evidently differing in form, while avoiding all other plants. 

 I had, indeed, seen the hive-bee mistake the flowers of 

 Ranuncuhcs arvensis for those of R. bnlbosus, those of 

 Trifolinin repens for those of Trifolium fragifernm many 

 times, but had then never seen it make so great a mistake 

 as that I have recorded of the humble-bee. From this I 

 concluded that the hive-bee is more practised in distin- 

 guishing various species than the humble-bee. As, how- 

 ever, I later saw the hive-bee go from the blue violet to 

 a hyacinth of the same colour, and back again, I felt con- 

 vinced that the grounds of my conclusion were somewhat 

 defective, and I can only leave the decision of this question 

 to further observations. As far as my own experience is 

 concerned, I am inclined to beheve that the hive-bee, as 

 well as all other bees which we see preferring special 

 families of plants, are much more led by colour and size 

 than by any clear apprehension of the form of the flowers. 



A. J. G. D. 



AN ACCOUNT OF DUPLEX TELEGRAPHY 



'T^HE introduction of the duplex system of working not 

 -^ only upon land-lines, but on sub-marine cables, is 

 without doubt the most important advance recently made 

 in electric telegraphy. 



Duplex telegraphy may be defined as the art of tele- 

 graphing in opposite directions simultaneously along one 

 line wire. 



It is claimed by M. Zantedeschi in papers read before 

 the Academy of Sciences, Paris, in 1855, that as early as 

 1829 he had suggested and demonstrated the possi- 

 bility of working ''duplex;" but until the year 1853 

 there do not appear to have been any noteworthy 

 attempts made to effect it practically. In that year, Dr. 

 Gintl, a director of Austrian telegraphs, described a system 

 of duplex telegraphy to the Academy of Sciences, Vienna, 

 and practically tested it on the land-lines between Vienna^ 

 and Prague. 



The principle underlying this and all other systems, is 

 that the outgoing currents at a station shall not sensibly 

 affect the receiving instrument there, while, at the same 

 time, the latter is free to be affected by the incoming 

 currents, so to speak, from the other station. That is tc 

 say, no signals are made at a station by its own sending 

 ■currents, unless when these are interfered with by the 

 sending currents of the other station. 



Gintl's plan was as shown in Fig. i. The receiving 

 instrument, R I, was wound by two separate wires, one 

 long and thin, the other short and thick. The long wire, 

 «hown by a full line, was connected at one end to the line 

 L, and the short wire, shown by a dotted line, was con- 

 nected at one end to a local, or, as it was called, a " com-- 



