INFUSOEIA. 



[ 420 ] 



INFUSORIA. 



Some Infusoria live in very briny ■water ; 

 and some can exist at a temperature of 

 120° Falir.; but their numbers diminish -with 

 the cold of winter, although a few can exist 

 when frozen in ice. Hardy as they are as 

 a class, it is therefore very remarkable to 

 witness the succession and disappearance of 

 ditierent genera during a comparatively 

 short time in infusions and natural waters. 



Diffusion, ^-c. — When we consider that 

 the multiplication of the Infusoria by divi- 

 sion takes places according to a geometrical 

 progression, also that they need only be- 

 come encysted to produce swarms of germs, 

 we can ea-ily understand their rapid pro- 

 pagation in liquids ; when also they will 

 resist a degree of cold =8° F., and an ele- 

 vated temperature of 2t)0° F., or even de- 

 siccation, without destruction, and when 

 their minute size is added, we can readily 

 understand their almost universal diffusion. 



As we have stated, a drop of water can 

 scarcely be found which does not contain 

 some Infusoria. Many of them wall only 

 live in fresh or sweet water, whilst others 

 are found only in decomposing and even 

 putrid water containing clecomposing ani- 

 mal and vegetable substances; others, 

 again, are only met with in salt or brackish 

 water. Those existing in fresh water may 

 be collected in ordinary wide - mouthed 

 bottles, a drop of which may be removed 

 by the dipping-tube ; any individual one 

 perceptible to the eye may be withdrawn 

 by the same means. Their natural move- 

 ments are best watched in the live-box ; 

 but these movements greatly interfere with 

 the observance of the contractile vesicles 

 and general minute structure, which is best 

 seen when they are simply confined be- 

 tween the slide and cover, in a small 

 quantity of water. A good plan for arrest- 

 ing their motions is that of warming the 

 slide containing thorn over a caudle or lamp 

 for a short time. Many Infusoria live only 

 in particular kinds of infusions, just as cer- 

 tain plants live only upon particular kir.ds 

 of soil ; and these infusions should be pre- 

 pared by adding cold fresh water to the 

 vegetable or animal subtances (the water 

 being in considerable excess), and allowing 

 the mixture to remain for a time. Even in 

 infu.-ions of many powerful poisons, as of 

 Nux vomica, Cevadilla, &c., they will not 

 be found absent; and Dujardin noticed 

 thattheirdevelopment was greatly promoted 

 by the addition of certain salts to the solu- 

 tious, as phosphate and carbonate of soda, 



phosphate, nitrate, and oxalate of ammonia 

 (really, the more recently so-called Pasteur's 

 liquid) ; and this author was inclined to 

 believe that some of these salts become de- 

 composed in the presence of the organic 

 matters, yielding nitrogen to the Infusoria ; 

 he also states that oxalate of ammonia dis- 

 appears entirely under these circumstances. 

 The following are the most common In- 

 fusoria found in natural waters or infusions 

 of vegetable or animal matters : — 



AmpMleptus fasciola. Monas guttula. 



Budo saltans. tertno. 



socialis. Oxytricha iieUioneUa, 



Chilvdon cucullulus. Paramecium aurelia, 



CJiilomonas parame- chrysalis. 



ciiim. colpoda. 



Chlamidomonas pul- milium. 



visculns. Polytoma tivella. 



Coleps liirtus. Stylonichiapusf.idata. 



Colpoda cxcidlus. mytihis. 



Cyclidium ylaucoma. Trachdins lamella. 



Euplotes cliaron. Tricltoda pura. 



Glaucoma scintillans. TricJiodina grandi- 

 Leitcophrys carnium. nella. 



I'yriformis. Uvella ylaucoma. 



Monas crepusculum. Vorticclla convallaria. 

 yliscens. microstoma. 



Some of the Infusoria are phosphorescent, 

 and impart a luminous property to sea- 

 water. This has been distinctly observed 

 in the following species : — Proroccntrnm 

 micans; Peridinium michaelis, P. micans, 

 P. fusus, p. furca, and P. acuminatum, 

 SynchcBta haltica, and a doubtful species of 

 Stent or. 



Slender needle-like crystals of sulphate 

 of lime have been observed affixed to the 

 bodies of the Infusoria, probably derived 

 from the water in which they live. 



The Infusoria are difficult of preserva- 

 tion. Some of them will exhibit their cha- 

 racters when dried, the cilia and vacimles 

 remaining very distinct, as also the striae 

 upon the integument. Others are but little 

 changed by a concentrated solution of chlo- 

 ride of calcium, or dilute glycerine. Solu- 

 tion of chromic acid or of bichloride of mer- 

 cury will answer with some of them, al- 

 though they are rendered somewhat opaque 

 by these reagents, which is sometimes an 

 advantage where they are naturally very 

 transparent. Osmic acid has been found 

 very useful in killing them so instan- 

 taneously, that the cilia remain as in 

 the living state. A saturated solution of 

 iodine in iodide of potassium acts like o^rmic 



