ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 265 



II. Theory of Wallace (1870) rejecting any laud connection what- 

 ever between the respective parts. 



Ortmann accepts Hooker's general i<lea, as well as Rutimeyer's 

 Antarctica theory, with the restrictions put upon it by Hedley. 



Influence of Alterations in Salinity.* — Erland Nordenskiold has 

 made an interesting study of the changes which occur in the fauna of 

 shore-pools when the salinity is increased or decreased. Thus tho 

 Copepod Harpacticm fulvus passes into a state of latent life when the 

 salinity exceeds about 9 p.c, may remain so for at least a week, and 

 becomes active again if the water is once more diluted. A somewhat 

 similar capacity is exhibited by Litorina rudis. 



Action of Neutral Salts on Ciliated Cells.f — Dr. M. Genkin finds 

 that the behaviour of ciliated cells (of the nasal mucous membrane) 

 affords an approximate test of the tonicity of solutions. If the dis- 

 solved salt, &c., has no chemical effect on the proteid molecules of the 

 cell-plasm, and if the concentration admits of the ciliary movement 

 continuing, the period and the character of the movements show 

 whether the solution is isotonic or not, and shrivelling or swelling is 

 a sign of hyper- or hypo-tonicity respectively. 



Behaviour of Nucleated and Non-Nucleated Red Blood-Corpuscles { 

 — R. Quinton relates experiments showing that when the two kinds 

 of red blood-corpuscle are placed in a solution of urea, an equilibrium 

 is established as regards the nucleated, but not as regards the non- 

 nucleated corpuscles. The haemoglobin diffuses out from the latter, as 

 was shown by Hamburger, Gryns, and Hedin. With nucleated corpuscles, 

 Quinton shows that this does not occur ; an equilibrium is established. 

 But this lasts for a'limited time, varying with the concentration. Then 

 haematolysis sets in. 



Permeability of Branchial Membranes.§ — Leon Fredericq dis- 

 tinguishes three types of branchial membranes, according to their 

 degree of permeability. In the first, the membrane is permeable to 

 water, to diffusible substances dissolved in water, and to gases, and is 

 entirely comparable to the membrane of a dialyser. This is exemplified 

 in the gills of the octopus and those of the crab Maui, where the blood 

 has the same molecular concentration, and is as rich or as poor in salts 

 as the surrounding water. In the second type the branchial membrane 

 is permeable to water and to gases, but not to dissolved diffusible sub- 

 stances. It is comparable to the " semi -permeable " membranes of Moiitz 

 Traube. In such cases the blood has the same molecular concentration 

 and the same osmotic tension as the surrounding medium, but is much 

 poorer in salts. This is exemplified in certain plagiostome fishes, where 

 the blood is poor in inorganic salts, but rich in organic diffusible sub- 

 stances. In the third case, the branchial membrane is permeable only 

 to gases, but impermeable to water, dissolved diffusible substances, and 

 colloids. It is then comparable to a thin sheet of caoutchouc, and the 

 blood possesses a different molecular concentration, osmotic tension, and 



* Ofversigt k. Vetensk. Akad. Forhandl., 1900, pp. 1115-27 (1 fig.). 



t Biol. Centralbl., xxi. (1901) pp. 19-22. 



X Comptes Rendus, cxxxii. (1901) pp. 347-50. 



§ Bull. Acad. Roy. Belg., 1901, pp. 68-70. 



