58 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the group. In several cases the hard parts only were available, and it 

 is on the basis of these that the genera and species are defined. The 

 author recognises five geEera, Mesocena, in which the skeleton occurs 

 in its simplest form, JUictyocha, Disteplianus, Cannopilus; in all these 

 the skeleton is constructed out of hollow rods of silica, while in Ebria the 

 rods are solid. All the species are very variable, and on the whole the 

 peripheral spines seem longer in the forms from the colder regions of 

 the sea than in those from the warm regions. 



Megastoma entericum Grassi.* — Prof. Rudolph Metzner has ob- 

 tained an abundant material of this parasite from the intestine of the 

 rabbit, and has been able to make some observations on the finer details 

 of structure. The organism in life has the body prolonged into a long 

 vibratile tail furnished with two terminal flagella. But in spite of its 

 active movements, this tail is not the main organ of propulsion, the 

 locomotor function being discharged by the " middle flagella " of the 

 body. In addition to these two middle flagella there are two anterior 

 and two lateral flagella. In each case there is a basal swelling, which 

 is obviously the centre from which the movement starts. From these 

 knob-like structures non-motile prolongations of the flagella extend 

 inwards through the protoplasm. Internally there is not only a nucleus 

 divided into two halves united by a bridge, but also in very many cases 

 another body of variable form, lying near the insertion of the middle 

 flagella. The author believes that the above-mentioned prolongations 

 of the flagella constitute a system for the transmission of stimuli, which 

 pass first to the " central body," and from it to the nucleus, thence, 

 perhaps, to the middle flagella, the main organs of locomotion. The 

 anterior, lateral, and caudal flagella may thus be regarded as a kind of 

 feelers connected with a central organ. The author briefly compares 

 these results with those of other investigators of other flagellates or of 

 ciliated cells. 



Trypanosoma in Fishes, f— A. Laveran and F. Mesnil describe 

 Trypanosoma remahi sp.n. from a fresh-water fish (brocket), Tr. solese sp. n. 

 from the sole (in four cases), and Trypanojolasma borreli g. et sp. n. from 

 Scardinius erythrophtTialmus. 



Mew Microsporidian. % — C. Yaney and A. Conte describe Pleisto- 

 pJwra mirandellse g. et sp. n. from the ovary of the fish Alburnus 

 mirandella. There are small cysts forming microspores and large 

 cysts forming macrospores (evaginating a very long filament in iodised 

 water). All the spores have a nucleus like a double T at right angles 

 to the longitudinal axis ; this has been seen by the authors in Henneguya 

 tenuis, Glugea bombycis, and Nosema varians. The eggs of the fish are 

 invaded by amoeboid forms which produce the spores. The micro- 

 spores are more resistant, and probably spread to other hosts; the 

 macrospores and the amoeboid form probably spread on the host itself. 



Sex-Elements in Stylorhynchus. § — Louis Leger makes another of 

 his interesting communications on the reproduction of Stylorhynchid 



* Zeitschr. wiss. Zool., lxx. (1901) pp. 299-320 (1 pi.). 



t Comptes Rendus, cxsxiii. (1901) pp. 670-5. t Tom. cit., pp. 644-6. 



§ Tom cit., pp. 414-7. 



