n'x 



ZOOLOGY AND BOTANY, MICKOSCOPY. ETC. ' 47 



111 Prowazekella and Tetramastix (including part of 3foiiocerco)nonas) 

 there are granular perinuclear mitochondria of a glycoplastic nature. In 

 Mo)iocercomonas and Polymastix (which should be uriited) there are 

 mitochondrial granules in front of or around the nucleus. In Emba- 

 domonas and Chilomastix there is an intranuclear cap of siderophilous 

 granules, which, as Miss Mackinnon has noted, may be sometimes extra- 

 nuclear ; it is equivalent to perinuclear mitochondria. In Protricho- 

 monas there are mitochondrial granules scattered in the cytoplasm, 

 which often condense into a parabasal body apposed to the nucleus. In 

 Entrichomastix lacertse siderophilous granules form an incomplete peri- 

 nuclear cupola ; in E. motellse there is the same, and the axostyle also 

 bears mitochondrial granules. In IVichomonas the disposition of the 

 mitochondrial granules is diverse, but specific. In Hexamastix there is a 

 perinuclear corona ; in H. iermiUs there are also endo-axostylar granules. 

 In Octomastix g. n. ( = Hexamitus pro parte) there are two median 

 siderophilous granules. In Octomitus mtestinalis the two axostyles are 

 surrounded by a zone of minute dust-like mitochondria, which periodi- 

 cally produce glycogen. 



Ecology of the Protozoa.* — Leon Augustus Hausman discusses the 

 different types of Protozoan habitats and associations. Of great im- 

 portance for the localization of species are — light, character of food, 

 temperature of the water, chemical content of the water, presence or 

 absence of enemies. In characteristic marsh pools the predominant 

 forms are: — Amoeba Umax, A. proteus, A. radiosa, Arcella vtdgaris, 

 Carchesmm imlypinum, Codonodadkmi itmbellatum, Coleps hirtus, Difflugia 

 acuminata, D. corona, B. ghbalosa, Eugbjpha alveolata, Oikomonas, 

 Peridinmm cinctum, Stylonichia mytilus, 8. pustulata, Stentor polymorphus, 

 Symtra uvella, Trinema acmus, Vorticella microstoma, and V. nutans. 



In clear cold waters, lacking plant growths, with quartz and shale 

 sands free from organic silt, the predominant forms are Astasia, 

 Holophrya, Holostichia verncdis, NostoJenus. In clear flowing water 

 with abundant plant life, with many diatoms, desmids, and Oscillatoria 

 on the bottom, the predominant forms are Amoeba proteus, Chdodon 

 (ucullus, Chilomonas paramocium., Colpidium, Golpoda iiiflata, Difflugia 

 constricta, D. globidosa, D. lobostoma, Holophrya, Holostichia ve'rndlis, 

 Monas Jluida, M. irregularis, M. dallingeri {?), Nostolenus orbicularis, 

 Oxytrichia peUionella, and Prorodon teres. 



In clear small rock pools with abundant decomposing organic 

 sediment, the predominant forms are Chilodon cucidJus, Chilomonas 

 parammcium, Coleps hirtus, Difflugia globulosa, Holophrya, Holostichia 

 vernatis, Monas, Paramecium barsaria, Trachelocerca olor, aud Vorticella 

 nutans. Of a rarer form the author writes, " Dileptus gigas is surely 

 the king of beasts among the ciliate Protozoa. It is entirely carnivorous 

 and its appetite is apparently insatiable. The prey is stung by the well- 

 developed trichocysts which Dileptus bears on its long ' neck,' and if too 

 large to be swept into the buccal cavity by the cilia is forced in by 

 writhings of the neck. The creature varies greatly in size, but is 



* Amer. Nat., li. (1917) pp. 157-72. 



