1-2, INVEKTEBEATE AXIMALS. 



ance of a single cell, consisting of an ill-defined membranous envel- 

 ope, filled with a, more or less granular sarcode containing fatty 

 granules, and having in it a little central bladder or vesicle — the 

 " nucleus " — which in turn encloses a solid particle or " nucleolus " 

 fig. 4, a and h). The outer covering or cuticle with which the 



Fig. 4.— Morphology and developiiieTit of dreg irinida faftcr Stein and Lielierkuliii), 

 a Sti/Jorhynchus oligacanthvs, a " dieystidean " Gregarine; ft Gregarine of tlie 

 eartli-worjn ("iiioiiocystidean"); c Tlie same encysted; d Further stage of the 

 same, with the contents divided into " pseudonavicellte " ; e Free "pseudonavi- 

 cellit', "; / Ainosbifnrni mass rif protoplasm liberated from a pseudonavicella ; 

 ;/ and h Active forms of /. All the figures are greatly enlarged. 



protoplasmic Ijody is enclosed may be quite smooth, ov it may be 

 furnished v\ith bristles or spines, and in some cases even cilia have 

 been obserNed. Bej'ond the nucleus and nucleolus no defiinte 

 oiLfans have been detected iu the (jlrcgarinie ; and all the processes 

 of assimilating forwl and getting rid of waste or injurious ]jroduct.< 

 must be effected by the general surface of the body. As we shall 

 see, lio\ve\XT, this is common in internal ]iiir;isites, which are not 

 jiecessitateil to live upon solid food, but which aie enabled to suljsi.^t 

 simply by imbibing the nutritive juices of their busts. 



Tlic following is a brief onlline of the process of reproduction, as it has been 

 oliscrvej in tlic <'rr'jarl)t<i\ sometimes in a single inilividual, sometimes in two 

 iniliviiluals which have come together and completely coalesced and melted 

 into one another. The <<n''jarina becomes completely motionless^ assumes a 

 globular form, and develops ronnd itself a thick structureless coat or envelope, 



