NATURE 



[Augtisf 9, 1877 



BIOLOGICAL NOTES 



Temperature of Trees.— Prof. Boehm has recently 

 investigated the temperature of trees in its relation to 

 external influences. His conclusions are these :— i. 

 The temperat\ire of the tree-interior is, during transpira- 

 tion, the combined expression of the air and the ground 

 heat. 2. The air heat is conducted transversally, the 

 ground heat longitudinally. 3. The longitudinal conduc- 

 tion is effected through the ascending sap-current, or 

 rather through transpiration. 4. A lowering of the 

 ground temperature during transpiration produces also a 

 depression of temperature in the tree-interior. 5. The 

 influence of the temperature of the ascending sap-current 

 decreases in the stem from below upwards, and from 

 within outwards. 6. Tlie amount of this decrease is 

 determined by the amount of the transversely- conducted 

 solar heat, and is in direct ratio with the diminution of 

 the volume of the stem part, and the approximation to the 

 periphery of the stem. 7. The lower part of the stem is 

 still under the full influence of the ground heat, or rather 

 of the ascending sap-current. 8. The vertical limit of 

 this influence is lost in the ramification of the tree. 9. 

 With exclusion of transpiration, and therewith of rise of 

 sap, the temperature of the tree is simply dependent on 

 that of the air. 10. A simultaneous coohng of the lower 

 and upper part of the tree completely equalises the 

 amounts of influence (opposite according to the height 

 of the stem) of the two cooling " moments." 



Latici FERGUS VESSELS IN PLANTS.— We notice a very 

 interesting Russian paper, by M. Schmahlhausen, just 

 appeared, " Researches on the Vessels of Plants." The 

 author shows that the growth of the vessels goes on in 

 the same manner as that of the mycelium of parasitic 

 Fungi in the tissues of plants, and thus refutes the often 

 expressed opinion that vessels in plants are analogous to 

 the blood-vessels in animals. 



Flora of New Guinea. — Baron Ferdinand von 

 Miiller's fifth contribution towards a list of Papuan plants 

 has recently reached us, and contains the remainder of 

 the species, with few exceptions, gathered last year by 

 Signor D'Albertis and Mr. Goldie, on their now famed 

 New Guinea exploration. In this list several new species 

 occur, notably a S/oa?iea, which Baron Muller has named 

 ^. paradisearum, from the fact that the tree, which grows 

 to the height of forty feet on the Upper Fly River, in- 

 habits the forest haunts of the birds of Paradise. The 

 fruits are described as closely approaching in size those of 

 S.jamaiccnsis, "thus far excelling any of the Sloaneas of 

 the eastern hemisphere, so far as they are known, in the 

 magnitude of the fruit." The discovery of Na^sia 

 Rumphii is interesting, from the fact that no other conifer 

 is reported from New ("ruinea, except Nagda Iheveteafolia, 

 and an Araucaria by Beccari. 



The Segmentation of the Head. — By slow degrees 

 an approach is being made to a true understanding of 

 this most difficult and interesting ciuestion. The old 

 explanations by archetypes and by the structure of the 

 highest- developed skulls, have fallen into disfavour. 

 Attempts to settle the cranial segments by considering 

 the distribution of nerves in the adult have been shown to 

 be unsafe, because nerves are necessarily adaptational in 

 their character and liable to the greatest modification on 

 changes taking place in the organs they supply. The 

 development of nerves, however, is a much surer guide, 

 showing primitive and fundamental characters. The 

 nerves behind the ear are five in fishes, although the 

 number of strands of which the vagus is made up in 

 some cases points to a loss of distinct nerves and segments 

 in the hinder part of the head. The auditory and facial 

 nerves originate as one, so that the auditory appears as a 

 specialised portion of the facial. The trigeminal like- 

 wise arises as a single nerve, and in front of this there is 



no nerve having a similar history to these and the spinal 

 nerves. Thus we have an indication of seven segmental 

 nerves issuing from the brain-case. When the visceral 

 clefts are considered, we find in sharks six clefts indi- 

 cating seven segments, or one more if the mouth be 

 regarded as a cleft. The head-cavities between the outer 

 wall of the head and the mucous membrane of the 

 throat, discovered by Mr. Balfour in sharks, furnish a 

 similar number. They are eight in all, one preman- 

 dibular, one mandibular, one hyoid, and five branchial. 

 Thus the examination of three sets of organs leads to 

 the assignment of eight body segments to the head. But 

 the question is far from being settled so long as' the 

 brain-case itself and the brain cannot be satisfactorily 

 explained. 



The Capercailzie in Northumberland.— It is 

 well known that this fine bird, originally indigenous in 

 the British Islands, became extinct, and was reintroduced 

 into the Scottish Highlands some forty years ago by the 

 late Marquis of Breadalbane. Earl Ravensworth has 

 recently been endeavouring to naturalise the capercailzie 

 in large tracts of pine wood in Northumberland, on the 

 edge of moors and wild crags, furnishing various berries 

 which form its favourite food. In 1S72 a cock and two 

 hens were reared ; but the male bird got destroyed. In 

 1873 two settings of eggs were hatched, but owing to a 

 wet summer all the young birds perished after nearly 

 arriving at maturity. In 1874 four fine birds were reared 

 to their full growth, one of which, a male, still survives. 

 In I S76 fifteen chicks were hatched out of twenty eggs, 

 and three cocks and four hens grew to maturity. But 

 the stock has become reduced to five individuals, three 

 males and two females, all in good health. It appears 

 that a difficulty arises from some deficiency in diet or 

 conditions which is at present unknown. Although ex- 

 tremely wild and shy by nature, and flying long distances, 

 capercailzies are yet most indolent, and unwilling to move 

 from places to which they are familiarised. Their colour 

 assimilates very closely with the Scotch fir, so that it is 

 exceedingly difficult to distinguish the male bird when 

 seated on a branch. The male is very ferocious, and 

 makes extraordinary gesticulations during the season of 

 courtship i the hen may even be killed by his fierce 

 advances. 



Evolution by Leaps. — Mr. Thomas Meehan has 

 described before the Academy of Natural Sciences of 

 Philadelphia a case of sudden change of characters in 

 some branches of a " smoke-house " apple tree, which bore 

 clusters of flowers at the ends of young shoots, flowering 

 six weeks after the ordinary blooms from spurs, and yet 

 maturing fruit at the same time as the old spurs. This 

 fruit, however, was very unlike the smoke-house fruit, the 

 fruit stems being long and slender, and the fruit flattened. 

 The change was so great that a botanist would have no 

 hesitation in describing the form as a new species ; and 

 there appeared no reason why the law which jjroduced 

 this modification might not simultaneously act on all the 

 trees in a district. At any rate here was an appearance 

 which served to show how new species might arise in 

 nature. Mr. Meehan, however, did not allude to the 

 difliculty of reasoning from a change in a cultivated variety 

 to the operation of causes in a wild state. The case 

 can hardly be considered as decisive, although of much 

 interest. 



The Eucalyptus in the United States.— Mr. 

 Joseph Wharton has tried to acclimatise i;. ^/<VW«j in 

 Philadelphia, but although the plants grow well in green- 

 houses, they seem incapable of surviving the severe 

 winters, even though carefully covered with leaves and 

 earth. The winter test was only applied after the plants 

 had grown vigorously for some years, being protected in 

 winter and placed in the open air in summer. 



