Mr. II. J. Carter on the Organization of Infusoria. 117 



Tliat the diaplianc is structureless and transparent, so far as our 

 niicrosc(>()ie powers extend, may be seen by the travelling of 

 some kinds of Amcpbu across the field of the microscope, in 

 which the coating of the diaphane, though broader all round 

 than the diameter of the turbid mass of contents in the centre, 

 only now and then, when the light is favourable, comes into 

 view. The radii in Actiaophrys are wholly devoid of turbid 

 material, except towards the base; and the advancing border of 

 the Ama^bre generally is always trans])are!it (tigs. 2 a,'d a). But 

 whether gi-anules are mixed with it or not, the diaphane by 

 itself, that is the contracting material, in the present state of our 

 microscopic powers, must be characterized by transparency and 

 motion, without apparent structure. It has the same appearance 

 and i)olynior])hic power in Diffingia, Euyhjpha, and Arcella, as 

 in Ainop.ba ; but in Astasia and Euylena, though still possessing 

 great latitude in this respect, it can put forth no prolongations, 

 and, consequently, the prmiary forms of these families are never 

 entirely lost. This latitude is still more limited in Oxytricha, 

 Plcescunia, Paramecium, &c., though in many Infusoria of this 

 class it has still the power of temporarily ])roducing considerable 

 alteration in shape. It might be stated that the diaphane can- 

 not be demonstrated in these animalcules ; but the great power 

 of motion of their tegumentary covering, combined with trans- 

 parency, warrants the use of the term here just as much as in 

 lihizopoda, where it is only more striking, because, for want of 

 cilia, the animalcule is compelled to put it forth in delicate ex- 

 pansions and prolongations, in progression, and for the caj)ture 

 of its food; — indeed, these are the two great modes in which all 

 its vital movements are effected. 



Some might think, from what has been stated, that there is 

 no difFcrence originally between the pellicula and diaphane, and 

 that the latter passes into the former when the animalcule be- 

 comes encysted. But neither appears to be the case ; for if we 

 watch Amoeba or Euglena undergoing this process, the activity 

 and accompanying polymorphism of the diaphane are diminished 

 only by the thickening and consolidation of the cyst, until the 

 latter is fully formed, when they cease altogether. Subsequently, 

 however, in Euglena, when this animalcule becomes temporarily 

 encysted, the diaphane separates itself from the last layer of 

 pellicula which completes the cyst, and thus the Euglena be- 

 comes free within it ; after which it will force off the constricted 

 peduncle of attachment from the object to which the cyst may 

 have been fixed, and, ])rojecting its eilium through the broken 

 part, swim aljout for some time, initil (])erhaps by increase of 

 size) the cyst is altogether burst, and its liberation restored 



