28 



NATURE 



[January 5, 1922 



mediate in character between scion and stock. The 

 graft-hybrid is generally sterile, and therefore is 

 usually kept going by grafting. On the rare occa- 

 sions when seed is set it produces normal yellow 

 laburnum. 



In the account given by McFarlane in the Trans- 

 actions of the Royal Society of Edinburgh for 1892 

 the suggestion was made that the distribution of 

 characters is such that the graft-hybrid consists 

 apparently of a core of laburnum wrapped in a skin 

 of Cytisus. This supposition has been confirmed in 

 the more recent production of graft-hybrids by graft- 

 ing common nightshade on the stem of a tomato and 

 vice versa. In all cases the stock would appear to 

 furnish the core and the scion the epidermal tissues 

 of the "hybrid." 



This simple explanation, however, does not appear 

 to cover fully the graft-hybrids between medlar and 

 hawthorn obtained by Prof. Daniel, in one case of 

 which, at any rate, tissues were present which 

 differed from those of either parent. 



In general, therefore, graft-hybrids represent shoots 

 produced adventitiouslv near the point of grafting and 

 containing representation of the tissues of both plants, 

 in many cases, e.g. Cytisus Adami, so arranged that 

 the external tissues resembled those of the scion and 

 the internal those of the stock. There were, how- 

 ever, instances — e.g. quince and pear — in which an 

 intimate mixture. of the characters of stock and scion 

 appeared in the graft-hybrid ^^•hich may have been 

 accompanied by vegetative union of the cells, but no 

 clear case of this cytological process had yet been 

 established. . ■ 



The whole phenomenon of graft-hybrids requires 

 further investigation, particularlv in relation to cases 

 in which the "hybrid " is said to occur on the scion 

 far removed from the point of grafting, which may 

 turn out to be instances of bud variation, possiblv with 

 reversion. 



D' 



Fauna of African Lakes. 



^R. W. A. CUNNINGTON, leader of the third 

 Tanganyika Expedition (1904-5), has contributed 

 to the Proceedings of the Zoological Society of London 

 (December, 1920), a comparative study of the fauna 

 of the African lakes — Tanganyika, Victoria Nyanza, 

 Nyasa, Albert Nyanza, Edward Nyanza, and Kivu, 

 with special reference to the first-named. The results 

 of recent investigation, admirably summarised In this 

 memoir, lend no support to the" view put forward in 

 1898 by Mr. J. E. S. Moore, leader of the first and 

 second expeditions, that Tanganyika represents an old 

 Jurassic sea, and that its fauna Is of relict nature. 

 Of the six lakes, Tanganyika has by far the most re- 

 markable fauna — of Its 402 species 293 are endemic, 

 and 57 of Its 168 genera are peculiar to Its waters ; of 

 the 146 species of fishes 121 are endemic, and a 

 notable feature Is the high degree of specialisation of 

 the Cichlida?. the lake presenting the richest known 

 assemblage of this family. There is a large molluscan 

 fauna, and of the species of gastropods more than 

 two-thirds — the halollmnic forms (Moore) — exhibit a 

 marine-like appearance, and these are, without ex- 

 ception, endemic. Noteworthy is the absence of 

 Cladocera, and the relative scarcity of rotifers, which 

 may be correlated with the salinity of the water, and 

 especially with the excess of magnesium salts. Dr. 

 Cunnington points out that geological investigation 

 Indicates that the extensive beds of sandstone and 

 conglomerate which occur In the lake regions were 

 probably formed under fresh-water and terrestrial 

 conditions, that the trough in which Tanganyika lies 

 NO. 2723, VOL. 109] 



was apparently not formed until middle tertiary times.. 

 and that the lake had no outlet until recent geological 

 times. Experts have not accepted Moore's comparison, 

 of shells from the lake with marine fossil shells of 

 Jurassic age, or his views as to the primitive nature 

 of the halollmnic gastropods. The endemic species 

 in the fauna of Tanganyika are now held to be 

 specialised rather than primitive. The conclusion 

 reached is that Tanganyika owes its remarkable fauna 

 to a long period of isolation, sufficiently extensive for 

 the Inhabitants of the lake to assume the characters 

 of species and even genera distinct from those of the 

 neighbouring parts of the continent. 



University and Educational Intelligence. 



In connection with the Conference of Educational 

 Associations which is being held at University Col- 

 lege, Gower Street, W.C.i, the annual general meet- 

 ing of the Education Guild of Great Britain and 

 Ireland took place on December 30. The president of 

 the guild, Sir Wilmot Herringham, delivered the presi- 

 dential address, taking university education as his 

 topic. He commented on the lack of interest in uni- 

 versity education shown by the majority of people, and 

 emphasised the value of the inclusion of natural 

 sciences In a general education as a training in induc- 

 tive reasoning. There is also material gain by the 

 training of a number of skilled practitioners In 

 chemistry, physics, engineering, medicine, etc., but 

 the most important function of the university is dis- 

 covery. Taking examples from medical science only, 

 gas gangrene, surgical shock, and the effects of poison 

 gas were mentioned as specific problems arising during 

 the war in which investigations were undertaken with 

 success in university laboratories. Another Interesting 

 fact mentioned was that between 1838 and 1851 out 

 of every million people born in Great Britain 500,000 

 died before the age of forty-five years; In 1881 that 

 age had risen to forty-eight; and by 1891 it was fifty- 

 two years — an increase In average life due, at any 

 rate In part, to research and discovery accomplished 

 by men of science working in the laboratories of our 

 universities. 



According to the December Issue of the School 

 Science Review, the representatives of the Science 

 Masters' Association met the Joint Standing Com- 

 mittee of the Headmasters' Conference and Associa- 

 tion of Preparatory Schools in June last and made 

 certain suggestions for the teaching of science in pre- 

 paratory schools. As a result it was recommended 

 that (i) in the Common Entrance Examination the 

 scope of the geography paper be widened, that some 

 of the questions in the mathematical paper should test 

 a boy's knowledge of practical mathematics, and that 

 in the composition paper candidates should have an op- 

 portunity of showing a knowledge of natural science ; 

 (2) candidates for scholarships should be given an op- 

 portunity of answering questions on natural science 

 in a viva voce examination as well as in the general 

 paper ; and (3) at least one, and if possible two, periods 

 a week should be devoted in preparatory schools to 

 science. The council of the Association of Preparatory 

 Schools was at first unwilling to adopt any of these 

 proposals, but after they had been approved by the 

 Headmasters' Conference the council of the Associa- 

 tion of Preparatory Schools agreed to them by 12 votes 

 to 3. When this decision is carried into effect boys 

 in preparatory schools will have an opportunity* of 

 gaining some knowledge of science at an age when 

 all natural phenomena are of absorbing interest to 

 them — a privilege bovs in secondary schools have 

 enjoyed for some time. 



