cxliv GENERAL SUMMARY OF SCIENTIFIC AND 



to the two forms of the "germ theory * of Dr. Sanderson and 

 Dr. Beale, and, indeed, adverse to the holding of any germ 

 theory in the only form in which it may be at all tenable. 

 No doubt a lively discussion will be elicited, but we much 

 doubt whether any conclusion acceptable to all will be ar- 

 rived at. 



Infusoriae, etc. At a recent meeting of the Academy of Nat- 

 ural Sciences in Philadelphia, Dr. Leidy described a curious 

 rhizopod found in a mill-pond, and measuring -j-J-g- of an inch 

 in length. It moves slowly with a snail-like motion, and pro- 

 trudes numerous papilla? and processes which bristle with 

 rigid spicules, which can be shortened or withdrawn a pecul- 

 iarity that separates the animal so widely from its nearest ally 

 that it probably belongs to a distinct genus. It is therefore 

 named by Dr. Leidy Dinamoeba mirabilis. A very curious 

 and interesting discovery of what appear to be fresh-water 

 polycystinse has lately been made, and a paper embodying all 

 at present known with regard to them may soon be expected 

 from Mr. George W. Morehouse ; hitherto they have been 

 considered exclusively marine, and are found in the deepest 

 sea soundings, where, either from the solution of the carbon- 

 ate of lime or other cause, the foraminifera have entirely dis- 

 appeared. The lamented Professor H. J. Clark published 

 in 1866 in Sillima?i's Journal a paper in which he maintain- 

 ed that the sponge was an aggregation of flagellate infusoria, 

 a compound protozoan animal ; the same view had been sub- 

 stantially announced a little before by Mr. Carter. Haeckel 

 has more recently modified this view, contending that the 

 flagellate monads of Clark are simply cells lining the general 

 stomach cavity of the sponge, and that therefore it is not a 

 compound infusorian, but a more highly organized animal 

 related to the radiates. He regards the sponges and acale- 

 plue as having been evolved from a common ancestor, which 

 he terms Protascus. 



We note in the Monthly Microscopical Journal for May 

 the completion of the excellent series of papers by Messrs. 

 Dallinger and Drysdale, entitled "Researches into the Life 

 History of the Monads." Five different forms of these have 

 been thoroughly studied, and they name them respectively 

 the cercomonad, the springing monad, the uniflagellate, the bi- 

 flagellate, and the calycine, the latter so named from its pe- 



