288 RECORD OF CURRENT RESEARCHES RELATING TO 



studied, they were not found until the early part of the autumn. 

 That they are hardy, is evident from the fact that the water of the 

 jar in which they lived was frozen, yet they were alive and active 

 after the thawing of the ice. 



Leidy's Fresh-water Rhizopods of North America. * — This 

 important work, which has long been expected, has just been issued, 

 and is the result of a large amount of careful microscopical research 

 into the structure, development, and habits of these lowest forms of 

 animal life. 



Dr. Leidy divides the Ehizopods into five orders : I. Protoplasta, 

 II. Heliozoa, III. Eadiolaria, IV. Foraminifera, and V. Monera, 

 agreeing in this with the views of Schulze '\ ; the Protoplasta and the 

 Monera corresponding to Haeckel's Protista. Excepting a few of the 

 Monera section, fresh-water Rhizopods belong almost entirely to the 

 Protoplasta and Heliozoa, and all the fresh-water species described 

 are of these two groups, excepting one Foraminifer — Gromia terricola 

 — a genus exceptional among Foraminifera, in that it is repre- 

 sented by several species inhabiting both salt and fresh water. The 

 Protoplasta include the genera Amoeba, Difflugia, Nehela, Arcella, 

 and others ; and the Heliozoa, Actinoph-ys, Heterophrys, and others 

 allied. With regard to Monera, Dr. Leidy says : " Though Haeckel 

 has indicated and described a number of fresh-water species, I am not 

 sure that I have had the opportunity of finding any of them, excepting 

 perhaps the genus Vampyrella of Cienkowski, which he ascribes to 

 the same order." 



One of the most remarkable forms described is the Dinamoeha 

 mirahilis, from the cedar swamps of New Jersey. It is commonly 

 cream-white or greenish white in colour, but spotted often with 

 green, brown, and yellow, all the colours excepting the white being due 

 to the food-balls, which are chiefly the Desmids Diclymoprium and 

 Bamhiisina. It is a gluttonous feeder, and is commonly so gorged 

 with this vegetable food as to be more or less opaque. Every part 

 of the surface, including the pseudopods and posterior papillte, is 

 ordinarily bristled with exceedingly minute spicules or ridged cils ; 

 but after some hours these may disappear, or be represented by 

 minute molecules. A still more remarkable feature is the occurrence 

 of a thick investment of hyaline jelly, the outer surface of which is 

 defined by innumerable, exceediugly minute rods, standing perpen- 

 dicularly, which make the animal look as if surrounded by a nimbus 

 of Bacteria. In the movements of Dinamoeha, its jelly-like cloak 

 appears to be no obstacle, and the subulate pseudopods shoot through 

 and beyond it as if it did not exist. 



Another species of peculiar interest is Hyalosphenia papilio, a buff- 

 coloured or straw-coloured species, perfectly transparent, and remark- 

 ably constant in its form. The species of Nehela, particularly 

 iV^ collaris, N. Tiippocrepis, and N. ansata, are of special beauty. 



* Leidy, J., M.D., 'Fresh-water Ehizopods of North America,' 824 pp. 

 48 plates (4to, Washington, 1879) ; see ' Am. Journ. Sci.,' xix. (1880) p. 240. 

 t 'Arch. Mikr. Anat.' (1877) p. 21. 



