November 14, 19 12] 



NATURE 



the centra] cavity of the spring inflorescence. 

 The staminate flowers, set in a ring round the 

 outlet, are now ripe, and the issuing female gets 

 dusted by their pollen. Then she flies to the im- 

 mature figs of the summer generation (we are 

 still speaking of the wild fig-tree), which contain 

 only female flowers. In her fruitless search for 

 gall-flowers in which to lay her eggs, she pol- 

 linates the female flowers. So many Blastophagas 

 are deceived by appearances that whenever a wild 

 fig-tree is shaken in July or August, swarms of 

 the flies come out of the summer figs. Is it pos- 

 sible that they procure food for themselves there? 



Ravasini shows that in the wild fig-tree there 

 are only two sets of gall-flowers, one in the win- 

 tering, another in the spring inflorescences. He 

 believes that there are also only two sets of 

 Blastophagas, answering to the two sets of gall- 

 flowers. One female Blastophaga may sufifice for 

 an entire inflorescence, so that there is a great 

 superfluity of insects. 



In October the wintering inflorescences are 

 ready, and the later-hatched Blastophagas of the 

 spring generation enter them to lay their eggs in 

 the gall-flowers. The life-cycle of the insect is 

 thus completed. 



We must now add a few words about cultivated 

 fig-trees. 



When men began to plant wild fig-trees in their 

 gardens, they would, of course, propagate them 

 by cuttings. Now cuttings of the wild fig-tree are 

 found to reproduce the characters of the branches 

 from which they were taken. By taking cuttings 

 from branches destined to bear spring in- 

 florescences, trees have been produced in which 

 only the spring inflorescences regularly attain 

 complete maturity ; these trees are Caprifigs 

 (goat-figs), which are practically male. In the 

 same way, by using as the parent stock branches 

 which bear summer inflorescences, trees have been 

 produced which are entirely female. Of these two 

 the caprifig alone is capable of harbouring the 

 insect guest during its growth period. 



Two fig-trees, very different in appearance and 

 function, have thus been developed by the action 

 of man out of the single primitive stock ; they are 

 often called 'varieties, but Tschirch and Ravasini 

 show that they are really artificially produced 

 sexual forms of one and the same natural species, 

 viz. of the wild fig-tree. One proof is that seeds 

 of the cultivated fig-tree produce either caprifigs 

 or inferior fruiting figs. A further proof is yielded 

 by the fact that the female Blastophaga, when 

 laden with eggs, can only fly a very short dis- 

 tance. Hence we infer that she is adapted to a 

 monoecious fig-tree, in which all the forms of 

 inflorescence are to be found on one tree. The 

 cultivated fig-tree is practically dioecious, and 

 without artificial pollination ripens no seed. Only 

 one monoecious tree is known, which can be 

 regarded as a possible common ancestor of the 

 two interfertile forms, caprifig and fruiting cul- 

 tivated fig; this common ancestor is the wild fig- 

 tree. 



Fig-cultivators must have become early ac- 

 quainted with the Blastophaga and the effects of 

 NO. 2246, VOL. 90] 



its visits, for the female flowers of the fig remain 

 unfertilised if no Blastophaga enters them, and 

 unfertilised female inflorescences (in unimproved 

 fig-trees) fall off prematurely. To prevent such 

 failures, the expedient was successfully tried (ages 

 ago) of fastening to the female trees ripe staminate 

 inflorescences of the wild fig-trees. Blastophagas 

 and pollen were thus supplied together, and the 

 female inflorescences duly ripened. In course of 

 time the inflorescences of the wild fig-tree were 

 replaced by those of the caprifig, which answer 

 the same purpose, and are easily raised on the 

 spot. Thus arose the practice of "caprification," 

 which is essential to the production of the best 

 keeping or drying figs. 



The dried figs of commerce, which are all seed- 

 bearing, absolutely require fertilisation by the 

 Blastophaga, and this is most easily secured by 

 caprification. But if only fresh edible fruits are 

 desired, caprification may be dispensed with. 

 By long-continued selection it has been found 

 possible to create varieties in which the unfer- 

 tilised figs do not fall off prematurely, but develop 

 into a valuable fruit. The large, non-seeding, 

 sweet and juicy table-figs of north and mid-Italy 

 require no pollination at all. Ravasini calls this 

 the greatest triumph of fig-culture. 



We have not explained all that we should like 

 to explain, but enough, we hope, to send some of 

 our readers to "Die Feigenbaume Italiens," and 

 to make them look out for the further experi- 

 ments which Dr. Ravasini promises. 



L. C. M. 



NOTES. 

 The next meeting of the International Union for 

 Solar Research will be held at Bonn on Friday, August 

 I, 1913, and succeeding days. 



A Reuter message from Stockholm announces that 

 the Swedish Royal Academy of Sciences has awarded 

 the Nobel prize for physics for 1912 to M. Gustaf 

 Dalen, a Swiss engineer, the head of the Stockholm 

 Gas Company, and the prize for chemistry has been 

 divided between Prof. Grignard, of Nancy University, 

 and Prof. Sabatier, of Toulouse University. 



The council of the Royal Scottish Geographical 

 Society has resolved to award the Livingstone gold 

 medal to Captain Roald Amundsen and the society's 

 silver medal to Captain Egnar Mikkelsen, the leader 

 of the Danish expedition to north-eastern Greenland, 

 in recognition of their services to geographical science. 



We are glad to learn that the Chilean Government 

 has sent instructions to the Chilean authorities at 

 Easter Island to afford every assistance in their power 

 to the e.xpedition organised and led by Mr. and Mrs. 

 W. Scoresby Routledge. The main object of this 

 carefully planned and well-equipped expedition is to 

 make a topographical and archaeological survey of 

 Easter Island, the most remote of Polynesian islands, 

 which is famous for its megalithic monuments, of 

 which visitors to the British Museum have seen 

 examples in the portico. There are many problems of 

 extreme interest concerning the culture of the natives, 



