546 SUMMARY OF CURRENT RESEARCHES RELATING TO 



with the four present in the lakes of Holstein. One of the five — 

 Ceratium hirundinella — is common to both districts, while three of the 

 remainder constitute new species. Of these Peridinium ivillei sp. n. is 

 one of the largest of the known fresh-water forms ; it lives in both deep 

 and shallow water, and occurs at all seasons of the year. The most 

 abundant form is Ceratium hirundinella, which occurs alike in the great 

 lakes and in the small ponds, often in vast numbers. 



Tentaculifera. * — Bene Sand completes his monograph with an 

 account of his particular observations on Dcndrocometes paradoxus, 

 Ophryodendron belgicum, Podophrya limbata, 2 species of Tolcophrya, 

 6 species of Acineta, Solenophrya crassa, 4 species of Epdielota, and 

 Podocyalhus diadema. 



Mosquitoes and Malaria. - ! - — Dr. G. H. F. Nuttall publishes a brief 

 chronological account of the experimental work done by all the observers 

 who have studied malaria since the publication of Sacharoff's papers in 

 1893 and 1895. His object is to show the part played by the different 

 workers in the discovery of the relation of mosquitoes to malarial 

 disease, in order to settle some of the disputed questions in regard to 

 priority. The result of the chronological record is to emphasize the 

 importance of Ross's discoveries, both in themselves and as furnishing 

 a guide to subsequent investigators. 



New Gregarine.J — L. Leger finds that Pinnotheres pisum, so often 

 found in the common mussel, is infested with a Gregarine similar to 

 that which Frenzel described as Aggregata. The sporozoites are formed 

 directly within the cyst, without the appearance of sporocysts. As 

 these stages are found only in the general cavity of the body, though 

 other stages occur in the lumen and in the epithelium of the gut, the 

 author calls the parasite Aggregata coelomiea sp. n. The ccelomic cyst 

 presents some remarkable resemblances to the ripe oocyst of the malarial 

 parasite in Anopheles. 



Sporulation of Monocystis agilis.§ — G. Cecconi has made an inde- 

 pendent study of this subject. The nucleus of an adult is spherical, 

 with a distinct membrane and a large globular vacuolated karyosome. 

 This nucleus is destined to disappear when two Gregarines encyst ; the 

 karyosome loses its central position, comes into contact with the nuclear 

 membrane, and gives off part of its content. Thus arises a spindle — 

 the secondary nucleus — which gives origin by successive mitotic divisions 

 to a large number of sporoblast nuclei, while the primary nucleus 

 dwindles away. The sporoblasts having been definitely formed, they 

 conjugate in pairs, and young sporocysts result. These divide after a 

 fashion which may be described as intermediate between the direct and 

 the mitotic methods, and the result, after several stages, is the formation 

 of 8 spores, which develop into young Gregarines. 



Gregariniform Stage in the Cycle of the Malarial Hsematozoon.|| — 

 A. Billet, in following the development of Laveran's haamatozoon, has 



* Arm. Soc. Belg.. Micros, xxvi. (1899-1900) published 1901, pp. 13-119, (8 pis.). 



t Quart. Journ. Micr. Sci., xliv. (1901) pp. 429-41. 



j Comptos Rendus, exxxii. (1901) pp. 1343-6 (1 rig.). 



§ Bull. Soc. Bot. Ital., 1901, pp. 132-5. 



I! Comptes Rendus, exxxii. (1901) pp. 1433-5 (7 figs.). 



