79& 



NATURE 



[August i8, 192 i 



shows a marked progress in width and inclusiveness 

 of vision. A mass of valuable data has been accumu- 

 lated, and the Ministr\-, by becoming- acquainted with 

 those areas where disease is most serious, is in a 

 better position to advise and to urge measures of 

 control. Further, the Ministry must lead the way, 

 and by the recognition of those diseases most respon. 

 sible for heavv losses, it will be enabled to suggest, or 

 institute, policies which will lead to the prevention of 

 the present appalling waste of foodstuffs. 



The report for 1919 is divided into three sections, 

 the first being a tabulated and summarised list of 

 the correspondents' reports on Insect pests received 

 during the vear. The second section is a complete 

 and up-to-date hand-list of the authenticated fungus 

 diseases in the country, and if expanded and elaborated 

 would form a verv useful reference book for plant- 

 pathologists, filling a niche at present singularly 

 empty. The third section is a summary of meteoro- 

 logical data with which the incidence and spread of 

 disease might be correlated. The report is a notable 

 achievement, and a fine example of the solid scientific 

 work which, quietly and unassumingly, is being 

 carried out by this branch of the Ministry of Agri- 

 culture. Much credit is due to Messrs. Fryer and 

 Cotton, who, in the face of not a little discourage- 

 ment and lack of aid, have carried this vvork 

 through to such a pitch of efficiency and permafienf 

 value. 



There are naturally many features at which one 

 could cavil, but these are due primarily to the 

 exigencies of the incomplete and voluntary system on 

 which the field reporting necessarily is phased, and 

 upon the innate difficulties in the reporting itself. Thus 

 whilst it is important to learn that a particular disease 

 is present in certain localities on specific dates, the 

 really important thing in this connection is to find out 

 what, if anv, relation exists between the several out- 

 breaks, and what relation the outbreaks bear to 



climatic conditions and dispersive factors. The 

 acquiring of such knowledge, however, is a consider- 

 able piece of research, needing the whole-time services 

 of a large personnel of highly trained investigators, 

 and^ these the country does not possess, nor will it 

 until plant disease is regarded a little more seriously 

 by the university and the farming mind. Again, to 

 learn that "Mosaic Disease is present in tomatoes 

 grown in the open," is interesting, but one would 

 like to know exactly what percentage of the plants 

 are killed or sterilised by this disease, or of those in 

 bearing what percentage of a normal yield is ob- 

 tained, and what is the financial' loss incurred by the 

 trade? The present lack of standardised criteria in 

 loss estimation is very unsatisfactory. However, 

 these are questions easy to ask, and almost, if not 

 quite, impossible to answer, and only slightly detract 

 frorrii the value of this report as a foundation for 

 epidemiological study in plant disease. 



But the preparation of such a report as this has a 

 far greater value than its local interest. Plant 

 diseases are no respecters of diplomats or political 

 boundaries. The disastrous spread into this country 

 of American gooseberry mildew, or wart disease of 

 potatoes ; of citrus canker and chestnut bark disease 

 into America ; the wiping out of the coffee industry 

 in Ceylon by the introduction of the coffee leaf disease 

 into that island — the remembrance of these among 

 many examples that could be quoted, should convince 

 everyone of the critical importance of an accurate 

 and systematic survey of plant diseases in order that 

 undesirable aliens may be excluded, or if found to 

 be present, crushed whilst still limited in distribution. 



The control of plant disease in our crops is one 

 of the most vital factors in agriculture to-day, and in 

 the lean years to come, when every ounce of food 

 will be an asset, the knowledge gathered together in 

 such reports as this will be a very material aid in 

 the struggle to provide the nation's sustenance. 



Studies of Shore Fishes.^ 



N 



OT the least of the Danish marine expeditions 

 in the Thor, under the skilful hands of Dr. 

 Jobs. Schmidt, was that devoted to the careful search 

 of the Mediterranean and the sifting of the work_ of 

 Grassi and Calandruccio in regard to the spawning 

 of the eel and the murenoids. 



In the course of this work many young shore-fishes 

 were encountered, and M. Louis Fage has given 

 an excellent report thereon. Some of them are 

 common to British waters as well as to the Mediter- 

 ranean, whilst others, such as Macrorhamphosus, 

 Anthias, Callanthias, and Uranoscopus, are more 

 characteristic of the southern waters. Though the 

 shores of the Mediterranean are rich, they fall far 

 short of the plenitude and variety of the shore- 

 fishes of Japan. Of the twenty families encoun- 

 tered, thirteen have pelagic eggs and seven demersal. 

 The striking changes between the adult outline 

 and that of the young are well shown in such 

 species as Macrorhmnphosus scolopax, the gurnards, 

 Serrantis cabrilla, and Anthias sacer. The illustrations 

 appear to have been made from preserved specimens, 

 and in a characteristic form like the grey gurnard in 

 Its early stage the pectorals fall short of the actual 

 proportions (cf. Prof. Prince's figure from life, Trans. 

 Roy. Soc. Edin., vol. xxxv., pi. xvil.. Fig. 5). 



Perhaps the most interesting part of M. Page's 

 memoir Is the introduction, in which he discusses the 



1 Report of the Daniih Oceanographical Expeditions in the Mediter. 

 ranean, 1908-10. " Shore Fishes." By Louis Faee, of the Natural History 

 Museum, Paris. Pp. 154. (Copenhagen : And. Fred. H^st and Son, 1918.) 



NO. 2703, VOL. 107] 



problems connected ' with the reproduction of the 

 Teleosteans. Amongst other features, he believes with 

 Glard that the embryology is condensed as we advance 

 to the north, yet that the pelagic embryos are specially 

 adapted to the colder waters. Thus, taking the genera 

 Sebastes and Scorpaena, the latter having two sub- 

 genera, Hellcolenus and Scorpaena, It Is found that 

 Sebastes marinus Is rare south of the Faroes, and is 

 viviparous. The widely distributed Helicolenus dac- 

 tylopteris, Delar., reproduces in winter in northern 

 waters, and the larvae agree with those of other Scor- 

 paenidae. On the other hand, Scorpaena porcus and 

 5. scropha In' the southern waters are developed In 

 summer, and their early pelagic stages have enormous 

 pectorals for sustaining them. The larval stages of 

 some of the fishes from southern waters are prolonged, 

 e.g. Arnoglossus laterna, Will., as shown by Dr. 

 H. M. Kyle, undergoes metamorphosis In northern 

 water when i6 mm. long, but In the Bay of Biscay 

 when 26-30 mm. in length. 



M. Fage attributes the wide distribution of the 

 young forms of certain shore-frequenting species to the 

 cyclonic currents of the Mediterranean ; but he has to 

 except the young of the genus Callionymus. A wider 

 view of the subject, however, creates doubt as to 

 the general applicability of such an explanation. In 

 connection with the adaptations of the larvae he 

 forms two groups (after Dollo), viz. the nectique and 

 the plantique. The slow forms, especially the 

 benthal, develop organs for maintaining equilibrium 

 in the plankton, such as long ventral or pectoral fins 



I 



