26 SUMMAKY OF CUEEENT EESEAECHES RELATING TO 



positions determined by the lines of least histological resistance, but 

 their course is not directly influenced by the position of the blood-vessels 

 or capillaries. The author believes that the pigment is produced by a 

 katabolic modification of the cell-substance. 



Structure of Amphioxus. * — Eugen Burchardt has had very abun- 

 dant material of this much-investigated form, and has been able to make 

 out some new points. In regard to the coelom he finds that the com- 

 plexity of its relations is accentuated by the occurrence of individual 

 variation. The transverse canals, which are ccelomic in nature, consti- 

 tute a regular means of communication between the ccelomic canals of 

 the pharynx and the liver-ccelom, and serve to equalise the pressure in 

 the two sets of spaces. They do not afford a means of communication 

 between blood-system and body-cavity, as suggested by various authors. 

 The author succeeded in finding Lankester's " brown funnels," and in 

 addition two paired septa which form a chamber corresponding to the 

 28th segment, The septa must be regarded as persistent splanchnocoelic 

 septa, and are the only regions in which true connective-tissue originates. 

 The limited area in which this tissue is formed the author ascribes to 

 the fact that Amphioxus is to be regarded as degenerate. He finds that 

 the pharyngeal bars may contain cysts due to a coccidium named by him 

 Branchiocystis amphioxi, which is apparently a common parasite. In 

 the coelom of one specimen of Amphioxus an " encapsuled organism " 

 was obtained, whose affinities remain wholly doubtful, while in the food- 

 canal of other specimens an apparently new Radiolarian — Prismozoon 

 neapolitanum — was obtained. The paper contains a copious bibliography. 



Osmosis between Hsemolymph and Sea-Water. f — R. Quinton gives 

 a series of tables for starfish, lug-worm, Sipunculus, crab, lobster, 

 Aplysia, Sepia, &c, showing (a) the approximate equality of the salinity 

 in the internal fluids and in the surrounding medium ; (b) the rapid 

 change of the internal salinity when the external salinity is altered ; and 

 (c) that this is due to osmosis. There is no direct communication 

 (excejit in the starfish) ; the weight of the animal increases in a hypo- 

 tonic medium, diminishes in a hypertonic medium, and remains constant 

 when equilibrium is established. This must be due to osmosis, and it 

 is shown that salts as well as water pass through the body-wall. 



Osmotic Pressure in Internal Fluids of Selachians.^ — E. Rodier 

 finds that the blood-serum, the pericardial, the peritoneal, and the uterine 

 fluids, freeze at almost the same temperature as the sea-water. As their 

 saline composition is notably different from that of the sea- water, the 

 uniformity of congelation temperature is ascribed to the organic sub- 

 stances (urea, &c.) in the body-fluids, and points to osmotic equilibrium 

 between outside and inside. 



L' Annexe Biologique.§ — We have received the preface, table of con- 

 tents, and index of the fourth volume of this valuable record, which 

 deals with researches in general biology for the year 1898. 



* 



Jen. Zeitschr. Naturwiss., xxxiv. (1900) pp. 719-832 (9 pis.), 

 t Comptes Rendus, exxxi. (1900) pp. 905-8, 952-5. 

 t Tom. cit.. pp. 100S-10. 

 § Paris, 1900, xxvii. and 842 pp. 



