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IV 
CONTENTS. 
PAGE 
Transverse Segmentation and Internal Differentiation of Chromo- 
somes. By W. E. Agak, Glasgow University. (With Plates 
Studies on the Development of Echinoidea. II. The Early Larva 
of Echinocardium cordatum and the Result of Crossing 
this Species with Echinus esculentus. By Prof. E. W. 
Macbride, D.Sc., LL.D., E.R.S., Imperial College of Science 
and Technology, South Kensington. (With Plates 14 and 15) . 299 
The Experimental Hybridisation of Echinus railiaris. Echi- 
nus esculentus, and Echinus acutus. By G. Debaisibux, 
Assistant in Zoology at the University of Louvain (Belgium). 
(From the Imperial College of Science and Technologj", London.) 
(With Plate 16) . . . . .325 
On Paternal Characters in Echinoid Hybrids. By Cressvtell 
Shearer, Walter De Morgan, and H. M. Fuchs. (From the 
Laboratory of the Marine Biological Association, Plymouth.) 
(With Plates 17 and 18 and 4 Text-figures) . . . 337 
On the Morphology of the Leish mania of Italian Kala-Azar. 
Third Communication : Cytologi cal Researches on Leish mania 
in Cultures. By Dr. Arrigo Visentini. (From the Zoological 
Department of the Lister Institirte of Preventive Medicine and 
the Institute of Comparative Anatomy of the University of 
Rome.) (With Plates 19 and 20) .... 353 
The Transmission of Leishmaniosis by means of Cultures, and the 
Mechanism of the Natural Immunity in Kats and Guinea-pigs. 
By Dr. Arrigo Visentini. (With Plate 21) . . 373 
Herpyllobius arcticus. By Kathleen Haudon. (With 
Plate 22 and 4 Text-figures) .... 385 
CONTENTS OF No. 231, N.S., JANUARY, 1913. 
MEMOIRS : 
Stolon Formation in Certain Species of Trypanosyllis. By F. A. 
Potts, M.A., Fellow of Trinity Hall, Cambl-idge, and Demon- 
strator of Comparative Anatomy in the University. (With 
The Effects of Hypertonic Solutions upon the Fertilised Eggs of 
Echinus (E. esculentus and E. acutus). By J. Gray, B.A., 
Scholar of King’s College, Cambridge. (From the Laboratory 
of the Marine Biological Association, Plymouth.) (With Plates 
12 and 13) 
285 
Plates 23 and 23 bis and 8 Text-figures) 
411 
24 to 27 and 4 Text-figures) 
447 
