ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 421 



is to be explained on the ground that they are all of the " coral-reef " 

 type. The striking thing in the Maldives is that of forms known to 

 he " local " in their distribution, nearly all found were new, and not 

 only so, but they are separated from their nearest allies by divergences, 

 which amount often nearly to generic importance. The writer concludes 

 that the Maldives are an area of geographic isolation which has lasted 

 for a considerable period. 



Porifera. 



Spermatogenesis in Porifera and Coelentera.* — W. Gorich finds 

 that division goes on within the spermatocyst of Spongilla so actively 

 that nuclei can hardly be found in a state of repose — even when the 

 nucleus of the spermatid has not reached this state, the centrosomes, one 

 larger than the other, may be seen beside it. A further stage is : both 

 centrosomes move toward the periphery — the smaller one nearer the in- 

 side. The latter next moves towards the nucleus, and in doing so forms 

 a delicate thread extending towards the larger body. Almost at the 

 same tims the tail is formed. On the opposite side of the nucleus a 

 minute highly refractive granule appears at this stage, whose origin was 

 not traced, though the author believes that it arises from the centrosome. 

 Somewhat similar phenomena were observed in the sperm-development 

 of Aurelia aurita. 



Protozoa. 



Demonstrating Discharge of Contractile Vacuoles.! — H. S. 

 Jennings points out that it is possible with the greatest ease to demon- 

 strate that, in Paramecium and similar forms, the contents of the con- 

 tractile vacuoles are discharged to the outside. The method consists 

 in mingling a large quantity of finely ground Indian ink, or Chinese 

 ink, with the water containing the animals. The clear fluid from within 

 the vacuoles passes into the black and opaque surrounding water, where 

 it is absolutely conspicuous, as a white and shining spot. 



Using this method, Jennings has observed the discharge of the 

 contractile vacuoles in Parametrium, NassuJa and Oxytricha, and also 

 in various Rotifers. 



Trypanoplasma of the Minnow.* — Louis Leger gives a description 

 of Trypanoplasma borreli — a Flagellate from the blood of the minnow 

 (Phoxinus tern). It is also known in the Red-Eye, and is adjacent to 

 T. cypriai Plehn from the carp. 



* Zool. Anzeig., xxvii. (1903) pp. 64-70. 



t Tom. cit. pp., 656-8 (1 fig.). 



% Comptes Kendus, exxxviii. (1904) pp. S24-5. 



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