448 



NATURE 



[December 19, 1912 



The second phase of the life-cycle (sporogony) leads to 

 the formation of pansporoblasts, each of which be- 

 comes converted into a spore, which serves for the 

 transference of the parasite to a new host. The I 

 symptoms of this disease, which has been termed 

 microsporidiosis, vary ; inability to fly, crawling, dis- 

 location of the wings, abdominal distension, and "dry 

 dysentery," followed by early death, may be noted. 

 Warm weather favours the bee, damp aids the para- 

 site. The method of infection is contaminative. 

 Hives, comb, honey, and pollen from comb, bees' 

 drinking places, flowers, water from foliage, and dew 

 near infected hives have been observed to contain 

 spores. Some bees can adapt themselves somewhat to 

 tlTe parasite, which forms crops of spores within them, 

 and these bees act as reservoirs of the disease. 



Preventive measures seem to be of most value in 

 treating this disease. The only certain destructive 

 agent for Nosema spores is fire. All dead bees should 

 be burned, old combs and hives untreated by a 

 painter's lamp are to be avoided, and it should be 

 remembered that old wax is not sterilised by being 

 merely melted. Weak stocks of bees should not be 

 united, and great care should be exercised in import- 

 ing bees from other places in the British Isles or from 

 abroad. Provision of abundant honey and pure water 

 supply, together with scrupulous clealiness of the hive 

 and its surroundings, are great aids in the prevention 

 of microsporidiosis. 



Prof. Minchin directed attention to the fact that 

 hereditary infection of bees by iV. a^is had not been 

 found to take place, whereas the allied parasite (N. 

 hombycis) of silkworms penetrated the ovary, and 

 entered the eggs, so that the next generation was 

 born infected. The latter parasite was able thus to 

 tide over the winter. Hereditary infection of bees 

 with JV. apis was not necessary to enable the parasite 

 to tide over the winter, for it can pass the winter 

 in hibernating adult bees. 



A Sessile Ctenophore. 



Dr. Th. Mortensen gave an account of a sessile 

 Ctenophore — Tjalfiella trisioma — found attached to the 

 stems of Umbellula taken off west Greenland. This 

 Ctenophore is compressed, elongated in the transverse 

 plane, and has lost its costs. The apical organ is 

 rudimentary, being — as a static organ — of no use in' a 

 sessile organism. The tentacles are simple, and there 

 is a branching canal system, as in Coeloplana and 

 Ctenoplana. The animal is viviparous; its eggs de- 

 velop in brood-chambers on the sides of the body, 

 giving rise to cydippiform young, which swim, for a 

 short time, by means of their well-developed costae, 

 then become attached by the mouth and at once begin 

 to assume the adult form. Tjalfiella is closely related 

 to Coeloplana, and especially to Ctenoplana, and Dr. 

 Mortensen held that its anatomy and development 

 support the Selenka-Lang theory of the origin of Poly- 

 clad Turbellaria from Ctenophores. 



Mr. E. S. Goodrich expressed himself as unwilling 

 to accept the view that Polyclads were derived from 

 Ctenophores. But even if these two groups were re- 

 lated, they must have diverged in remote time, and it 

 seemed to him inconceivable that their common 

 ancestor should be still extant. Prof. Dendy did not 

 share this view. 



Papers on Hehninthology. 

 Dr. W. Nicoll gave a risximi of recent progress 

 in helminthology. He directed attention to the use 

 of internal instead of external features as the basis 

 of specific diagnosis, and to the correlation between 

 habit and systematic position, which is clearly brought 

 out bv the new method of classification. He noted 



NO. 2251, VOL. Qol 



the great importance of the discovery that infection 

 by Ankylostoma and Schistosomum takes place 

 through the unbroken skin. Turning to morpho- 

 logical questions, he directed attention to the so-called 

 " shell-gland " of Trematodes, pointing out that recent 

 researches have shown that the shell-substance is 

 secreted bv the "yolk-glands," and that the function 

 of the " shell-gland " remains unknown. Of interest 

 also is the discovery of the existence of a communica- 

 tion between the intestine and the excretory vesicle 

 in certain digenetic Trematodes. 



Mr. J. W. Chaloner has investigated a disease of trout 

 in Loch Morar, due to a larval Bothriocephalid (plero- 

 cercoid larva), found encysted in the wall of the intes- 

 tine and adjacent organs, the cyst-wall being formed 

 by the tissues of the trout. The larvre varied in length 

 from J to 8 in. The birds of the loch were examined, 

 and, in an adult merganser, a Diphvllobothrium— pos- 

 sibly the adult of the larva described — was found. All 

 the merganser were found to be infected with the 

 larval and adult sexual form of Schistocephalus gas- 

 terostei, obtained from the sticklebacks, which form a 

 large part of the food of these birds. 



Papers on Polychaeta. 

 Prof. W. C. M'Intosh directed attention to the close 

 structural resemblances between the genus Filograna, 

 which has an ooerculum for closing the tube, and 

 Salmacina, which has no operculum. It was shown 

 that the presence or absence of an operculum was not 

 a point on which great dependence could be placed, 

 since in the north — Shetland, Moray Firth, St. 

 Andrews — amidst vast swarms of those devoid of 

 opercula, a few occurred with them. Further, it was 

 shown that the opercula are exceedingly variable in 

 development, and that when they are absent the tips 

 of the branchial filaments show great susceptibility to 

 growths of a more or less conspicuous character ; 

 especially is this the case in Neapolitan specimens. 

 The branchial pinnje are variable in length according 

 to the age or surroundings of the specimen, and the 

 bristle-tufts of the anterior region likewise varv from 

 five to ten pairs ; yet, throughout the whole series of 

 those with or without opercula, the structure of the 

 bristles is precisely the same. Both forms are gemmi- 

 parous. After examining numerous examples and 

 noting the plasticity of the organs. Prof. M'Intosh 

 said he would prefer to refer all the forms to one 

 species of the genus Filograna. 



Mr. F. A. Potts gave an account of the habits of 

 a*new species of Phyllochsetopterus, found living in 

 shallow water off Vancouver Island. It lives in creep- 

 ing tubes of translucent material, which generally 

 possess several openings, each situated at the end of a 

 branch of the main tube. In nearlv all tubes more 

 than one individual is present, sometimes as many as 

 six. The tube is constructed, in the first place, by a 

 single individual, which is formed from a fertilised 

 egg; this worm propagates itself by autotomv, the 

 posterior part becoming detached and regenerating an 

 anterior region. Modification and branching of the 

 tube occur to suit the increasing population. Circula- 

 tion of water in the tube is maintained by the move- 

 ment of cilia on the median segments and by undula- 

 torv movements of the abdomen. 



Mr. Potts also described the formation, in Trvpano- 

 syllis sp., of reproductive buds, to the number of 

 one to two hundred, from a patch of tissue extending 

 over the ventral surface of the last one or two seg- 

 ments. Ectoderm and mesoderm alone take part in 

 the formation of these buds : there is an entire absence 

 of alimentarv canal. In T. gemmipara, from the 

 N.W. Pacific, bud-formation is accompanied by the 

 I- rapid addition to the stock of a tail of fottv to fifty 



