December 14, 1905] 



NA TURE 



16' 



eeedings at Cape Town by delivering a semi-popular lecture 

 on recent advances in our knowledge of seaweeds. Dealing 

 first with the attached shore vegetation, the lecturer pointed 

 out that, with the exception of a very few phanerogams, 

 this consists entirely of blue-green, green, red, and brown 

 algae. In the red algae the most important recent work 

 is that of Oltmanns, who has shown, in opposition to the 

 view maintained by Schmitz, that no real nuclear fusion 

 takes place in the auxiliary cells. In the brown algae 

 Williams's work on the Dictyotaceae has considerably 

 modified the views previously held regarding them. Not 

 only has he discovered motile antherozoids in this group, 

 but his work on their cytology points to the existence of 

 a definite alternation of generations. Farmer and Williams 

 had shown that in the Fucaceae the reduction of chromo- 

 somes takes place at the origin of the oogonium. In 

 Dictyota, however, as originally shown by Mottier, and 

 since confirmed by Williams, the reduction division occurs 

 in the mother-cells of the tetraspores. There would thus 

 appear to be in this plant two generations, precisely similar 

 in their external morphology, but fundamentally distinct in 

 respect of the number of chromosomes in the dividing 

 nucleus. Our knowledge of the floating oceanic vegetation 

 has been greatly extended by the members of the German 

 plankton expedition, and other workers. The lecturer 

 dealt with the distribution of this floating vegetation in 

 the surface waters of the globe, and described some of the 

 adaptations which prevent rapid sinking of the minute 

 forms composing it. 



Mr. R. P. Gregory discussed some of the problems of 

 heredity. He first gave a general account of Mendel's 

 principles of heredity, referring to some of the more recent 

 work on Mendelian lines. He then dealt particularly with 

 some new experiments conducted by Mr. Bateson and him- 

 self, on the inheritance of heterostyly in Primula. Although 

 certain irregularities were observed, on the whole the 

 characters of long and short style were inherited in the 

 usual Mendelian ratio, the short style being dominant, the 

 long recessive. Further experiments, conducted in the hope 

 of throwing light on the fact, observed by Darwin, of the 

 relative infertility in " illegitimate " as compared with 

 *' legitimate " crosses in Primula, were inconclusive. 



Prof. F. E. Weiss contributed a paper on the value of 

 botanical photographs. He pointed out that the mapping 

 of the plant-associations of any given district, and the 

 detailed study of the ecological factors concerned, can be 

 most usefully supplemented by good photographs showing 

 the general aspect and distribution of the vegetation. It 

 is important to have, not only general photographs of 

 various plant-associations, but also photographs of the 

 different members of such associations. Plant photography 

 can also be usefully employed in morphological, patho- 

 logical, and other studies. The truth of the author's 

 remarks was forcibly illustrated by a series of beautiful 

 lantern slides. Two committees are now at work collect- 

 ing botanical photographs and rendering them available 

 for teaching and other purposes. One, recently established 

 for the survey of British vegetation, is concerning itself 

 with British ecological photographs; the other, the British 

 Association committee for the registration of photographs 

 ol botanical interest, has adopted a wider scheme, and is 

 anxious to receive help from scientific photographers in all 

 parts of the world. 



An interesting discussion took place on educational 

 methods in the teaching of botany. The president (Mr. 

 Harold Wager, F.R.S.), who opened the discussion, was 

 of opinion that the methods usually employed, both in 

 universities and schools, neither develop real interest in the 

 subject nor afford an adequate training in scientific method. 

 He emphasised the importance of basing all courses of 

 botanical teaching on practical work, both observational 

 and experimental, such work to be carried out by the 

 students themselves. Lectures should be rather of the 

 nature of discussions upon the facts learned during prac- 

 tical work than merely informational. A good deal of 

 faulty educational method is due to the domination of 

 examinations. It is almost impossible for satisfactory 

 wurk to be done if teachers are compelled to follow set 

 syllabuses, which are generally so extensive as to leave 

 little room for originality on the part of the teacher. 



Several speakers agreed with the general conclusions of 



NO. 1885, VOL. 73] 



the president, but Mr. A. C. Seward. F.R.S., and Prof. 

 Douglas Campbell were inclined to lay more stress on 

 the importance of lectures, particularly where advanced 

 students are concerned. 



Miss Lilian Clarke contributed to the discussion a most 

 interesting account of her methods of teaching botany in 

 the James Allen School for Girls at Dulwich. She gives 

 no set lectures, but the girls make observations and con- 

 duct experiments, not only in the school garden, where 

 each girl has charge of a plot, but also in the laboratory. 

 The latter has been designed so as to admit as much light 

 as possible ; it can also be kept at a constant temperature, 

 so that practical work on living plants can be carried on 

 at all seasons of the year. 



South African Botany.— Mr. A. C. Seward, F.R.S., in 

 discussing the fossil floras of South Africa, gave a general 

 account of the plants characteristic of the Lower Karroo, 

 Stormberg, and Uitenhage series. He laid stress on the 

 need for further field work, as more material, particularly 

 petrified specimens for microscopical examination, is badly 

 needed to render our knowledge of these floras more 

 complete. 



Prof. A. Engler and Dr. R. Marloth - presented important 

 papers on the floras of tropical Africa and South Africa 

 respectively. 



Prof. Engler dealt with his subject largely from the 

 ecological point of view. Discussing first the meteor- 

 ological conditions of tropical Africa, he pointed out that 

 in every tropical country, where the altitude of the land 

 surface varies from sea-level to high mountains, practically 

 the same plant-formations can be distinguished, though, of 

 course, their systematic composition may be very different 

 in different cases. The author then enumerated the various 

 halophilous, hygrophilous, xerophilous and other form- 

 ations, with their subdivisions, finally discussing the 

 affinities of the flora as a whole. The dominant element 

 of the flora is one peculiar to tropical Africa, the plants 

 composing which are more nearly related to those of India 

 and Madagascar than they are to those of tropical America. 

 But besides this native element, we find in tropical Africa 

 other elements. Thus in the hygrophilous formations of 

 East Africa, Indian and Madagascan elements abound, 

 while in those of West Africa a distinct tropical Amerii an 

 element is found. A South African element is present, par- 

 ticularly in the shrub-formations of Angola and East 

 Africa ; a Mediterranean element in the north-east, 

 especially in Somaliland ; and lastly, in the high moun- 

 tains, many species belonging to a boreal element are 

 found. From the entire absence on these mountains of 

 many groups characteristic of northern regions, Prof. 

 Engler concludes that such northern forms as are here 

 found have entered by immigration, and are not the 

 remnants of a once widely spread Old World flora. 



The botanical regions proposed by Dr. Marloth in his 

 paper on the phyto-geographical subdivisions of South 

 Africa are somewhat similar to those suggested by Bolus, 

 Engler, and others, though differing in detail. The two 

 main divisions, very unequal in size, are A, the Cape 

 province, characterised by many endemic plants of more 

 or less south temperate affinities, and B, the palaio-tropical 

 province. The latter is again subdivided, according to 

 ecological conditions and floral constituents, into (i) the 

 grass-steppe regions, including the Bush-veld, High-veld, 

 Kalahari, and the Caffrarian countries; (2) the central 

 districts of Cape Colony, including the Karroo, the Karroid 

 plateau and Little Namaqualand ; (3) the western littoral; 

 (4) the forests of the south coast ; (5) the south-eastern 

 coast belt. 



Mr. J. Burtt-Davy contributed a paper on the climate 

 and life zones of the Transvaal. He divides the Transvaal, 

 according to altitude and climate, into three zones, which 

 he terms the High, Middle, and Low Veld respectively. 

 Each is characterised, not only by its native vegetation, 

 but also by the crops it is capable of producing. 



Mr. F. B. Parkinson gave an interesting account of 

 irrigation farming as carried on at the Orange River farm 

 at Baviaankrantz. To raise the water, chain and bucket 

 pumps are employed, working in shafts sunk at a sufficient 

 distance from the river to be above flood-level. The shafts 

 are supplied with water from the river by means of 10-inch 

 syphons. By judicious watering, winter cereal crops, and 



