548 



NATURE 



[October 27, 19 10 



and the following extract from the Agricultural Gazelle 

 0/ Nciv SouDi Wales (August 2) is of interest : — " The 

 Chief Quarantine OlTicer for Plants has informed the 

 L nder-Secretary for Agriculture of a most extraordinary 

 method whereby an objectionable weed might be broad- 

 casted throughout the State. It appears that, as an 

 advertising mediuin, some printed paper, representative of 

 a flying insect, has been sent to Australia, and the genius 

 who invented this particular style of advertisement, in an 

 endeavour to make it more realistic or uncommon, had 

 attached to each specimen the burr or seed of the noxious 

 weed ' Burdock ' {Arctium Lappa). The authorities in 

 Western Australia had called the attention of the Director 

 of Quarantine to the use to which the burr of this noxious 

 weed was being put. It is needless to say that business 

 firms stopped the issue of the advertisement under notice 

 as soon as they knew there was a serious objection to its 

 use." 



Burdock is a very troublesome weed, and it is clear 

 that our colonial friends have to be on the alert if they 

 are to prevent the introduction of new plants in the manner 

 outlined. 



THE LANCASHIRE SEA-FISHERIES 

 LABORATORY. 

 'T'HE eighteenth report of the Lancashire Sea-Fisheries 

 Laboratory (for the year 1909) contains an account of 

 work carried out at the University of Liverpool, at the 

 sea-fish hatchery at Piel, and at the Port Erin Bio- 

 logical Station. Mr. James Johnstone describes five 

 species of internal parasites of fishes from the Irish 

 .Sea, the three genera discussed being Lebouria, 

 Prosthecobothrium, and Echeneibothrium. The same 

 author reports on the measurements of some 55,000 plaice 

 from the district, curves representing the frequency of fish 

 at each unit of length for the most important fishing 

 grounds being given. The average weights of plaice at 

 each unit of length from various fishing grounds have also 



been determined. Taking Hoinckc's formula w = — /; 



100 

 where w is the weight in grams and ; the length in centi- 

 metres, the monthly variations in the value of k have been 

 calculated for several of the grounds. The value shows a 

 maximum in July, and the minimum appears to be in 

 January, at which time of the year very little food is found 

 in the stomachs of the plaice. 



.\ considerable section of the report is occupied by papers 

 on hydrographical work done in the Irish Sea by Mr. 

 Johnstone and Dr. H. Bassett. It is doubtful, however, 

 whether the comparatively slender data contained in the 

 papers. of the latter writer can be usefully employed in the 

 way suggested by him, in connection with the prediction of 

 climatic conditions over extended periods of time. Very 

 much more research will be. necessary before such predic- 

 tions can have any but a speculative value. 



The report concludes with a paper by Prof. Herdman, 

 Mr. A. Scott, and Mr. Dakin on plankton work carried 

 out off the Isle of Man in 1909. The paper as a whole 

 tends to confirm the doubts, w-hich have often been 

 expressed, as to the value of the quantitative methods of 

 plankton work, as at present practised. Until some trust- 

 worthv instrument has been devised for accurately measur- 

 ing the quantity of water w'hich has passed through ihc 

 net on each occasion, the elaborate methods of counting the 

 orcanisms captured would hardiv seem to repay the time 

 which must necessarily be employed upon them. 



ZOOLOGY AT THE BRITISH ASSOCHTION. 

 'IPHE attendance of zoologists at the meetings of Section 

 D was affected by the fact that the International 

 Congress of Zoology at Graz and the International Con- 

 gress of Entomology at Brussels had taken place so 

 recently. These meetings abroad were probably responsible 

 for the absence of a few of those who in previous years 

 have contributed papers to the section. The programme, 

 bring a little less crowded than usual, was taken at a 

 more comfortable pace, and reasonable time was available 

 for discussion and remarks on the various subjects under 



NO. 2139, VOL. 84] 



consideration. The attendance at the meetings of the 

 section was very satisfactory, especially in the circum- 

 stances, and the interest in the proceedings was fully main- 

 tained to the end ; indeed, the concluding meeting was one 

 of the best of the series. 



Coral Snakes and Peacocks. 

 The popular lecture, which for several years has been 

 a feature of the programme of the section, was given 

 before a large audience by Dr. H. F. Gadow, F.R.S., 

 who chose for his subject " Coral Snakes and Peacocks," 

 and illustrated his remarks by a series of lantern-slides in 

 colour. He first described some of the physical features 

 of Mexico, during a visit to which country his observa- 

 tions on coral snakes (Elaps) were made. The red, black, 

 and yellow markings of these snakes have been said to be 

 of the nature of " warning coloration," but Dr. Gadow 

 pointed out that, although the markings are conspicuous 

 when the snakes are lying in a dish or other vessel, the 

 colours commingle, especially in the dusk, with the 

 natural surroundings of the animal, so that it becomes 

 very inconspicuous. Coral snakes are entirely nocturnal 

 in habit ; they lie in hiding during the day, so that the 

 explanation of their coloration as " warning " is un- 

 warrantable. Many harmless snakes are coloured in a 

 similar manner to the coral snakes, e.g. among a large 

 collection of Coronella from various places in Mexico 

 examples of one species were found which seem to have 

 " mimicked " several of the colour patterns exhibited by 

 species of Elaps. But Dr. Gadow pointed out that the 

 specimens of Elaps and Coronella found in the same 

 locality do not exhibit the same colour pattern. Dr. 

 Gadow's conclusion, stated briefly, was that the resem- 

 blances in colour pattern between Coronella and Elaps 

 are instances of pseudo-inimicry. In the second part of 

 his address Dr. Gadow traced the gradual transition from 

 a comparatively simple feather with light and dark bands 

 to the " eyed " feather, with fully developed metallic 

 lustre, of the mature peacock's " fan." He then described 

 the retrogressive changes leading from the " eyed " feathers 

 to the modified feathers of the back and margin of the 

 " fan." 



Coccidia and Coccidiosis in Birds. 

 Dr. H. B. Fantham described his observations on the 

 life cycle of the sporozoon Eitneria (Coccidiuni) aviuiii, 

 which produces a form of " enteritis " in grouse, fowls, 

 and pheasants, especially in young birds. Resistant 

 oocysts of the parasite are voided in the feeces of the 

 infected birds, and are acquired by other birds in their 

 food or drink. A mature oocyst contains four sporocysts, 

 in each of which are two active motile sporozoites. After 

 the oocysts have been swallowed by a bird, the cyst wall 

 is softened by the pancreatic juice, the sporozoites creep 

 out and penetrate the epithelial cells of the duodenum, in 

 which they become rounded and grow, feeding passively 

 on the host cell, .^ftcr attaining a certain size, the 

 nucleus and protoplasm of the parasite — now a schizont — • 

 divides into a cluster of merozoites arranged en barillet, 

 i.e. like the segments of an orange. Very little residual 

 protoplasm remains after the formation of merozoites. 

 These small, vermicular merozoites glide away and invade 

 other cells, within which they grow to schizonts and 

 multiply. A number of generations of merozoites is pro- 

 duced in this way, and the destruction of the epithelium 

 and the derangements resulting therefrom in some cases 

 cause death of the host. In most instances some mero- 

 zoites pass down into the ca;ca, where they grow and 

 multiply, producing intense inflammation. Sooner or later 

 a limit is reached, both to the power of the bird to provide 

 nourishment for the parasites and to the multiplicative 

 capacity of the parasite itself, and then sexual forms are 

 produced. Some of the organisms become large and con- 

 tain much reserve food material. These are the macro- 

 gametocytes, each of which, after the maturation changes, 

 becomes a single macrogamete. Slightly smaller parasites, 

 with little or no reserve material, undergo nuclear multi- 



I plication and give rise to many minute biflagellate micro- 

 gametes, which disperse and swim away in search of 

 macrogametes. Each of the latter has precociously 

 I invested itself with a cyst wall, in which a micropvle is 

 1 



