578 SUMMARY OF CURKENT RESEARCHES RELATING TO 



ployed : the ventral surface always carries the mouth and the various 

 appendages which function in locomotion and in the production of the 

 nutrient currents ; the prebuccal and postbuccal regions vary greatly 

 in their proportional extent, and it would seem that the suppleness 

 and contractility of the body stand in an inverse relation to the 

 development of the prebuccal region ; this may be distinguished into 

 a peristome and a lateral area ; and they, also, differ in the pro- 

 portional extent to which they are developed. Four kinds of 

 appendages may be distinguished : vibratile cilia ; cirri, which are 

 stylet-shaped, and much larger at their base than at their free-end, 

 and which may be abdominal, transverse, or marginal ; setsB, which 

 are filiform, homogeneous, and simple, but rigid like needleSj and 

 which may be dorsal or caudal ; the latter are much longer and 

 stronger ; lastly, the vibratile membranes are either those properly so 

 called, or are buccal " membranelles." 



Actinotrocha saltans, Gonostomum pediculiforme, Holosticha lacazei 

 n. sp. (seas near Algiers), H. muUinucleata n. sp, (port of Algiers), 

 Uroleptus roscovianus n. sp. are then described. 



The author proposes to replace the terms Protozoa and Metazoa 

 by those of Cytozoa and Histozoa. 



Attention is directed to the characters of the naked Infusoria, 

 which are not all members of the group Acinetje, but are found also 

 among the Ciliata. The existence of forms without an integumentary 

 layer shows that its presence or absence is in no way associated with 

 the grade of development to which a Cytozoon may arrive, but that the 

 protoplasm is ready to take on the most varied forms and structure, 

 without the addition of an external protecting layer. The views of 

 Hackel as to the typical constitution of the integument of an 

 Infusorian are discussed, and the conclusion is come to that the 

 " cuticular layer " is perfectly distinct from the skeletal cuticular 

 formation, that the ciliary and myophanous layers have no existence, 

 and that the layer of trichocysts is a part of the sarcode and not of 

 the integument. Contrary to the views of Hackel, with regard to 

 whom Maupas expresses himself in the most energetic manner, the 

 integument of ciliated Infusoria is looked upon as corresponding 

 morphologically to the membrane of the cell, of which it has all the 

 physical properties. The integument is, in fact, defined as any distinct 

 superficial layer, which is intimately applied to the surface of the 

 cell, and lives the same life as it does. The various conditions under 

 which it presents itself are then described. 



The physiological properties of the sarcode or cytosome strike one 

 by their resemblance to those of the body of the Ehizopoda, and lead 

 one to think that an Infusorian may be defined very exactly as a 

 Rhizopod inclosed in an integument and provided with appendages 

 which are destined to fulfil the external functions which the sarcode 

 of the Rhizopod performs for itself. 



The author's observations on the trichocysts are stated by him to 

 confirm those of Allman. The doubly refractive bodies which have 

 been ordinarily regarded by those who have studied them as urinary 

 concretions, offer us an important specific character, as they may be 



