310 Miscellaneous. 



which is propagated from the extremity towards the base, and 

 which is followed by a sudden straightening of the whole arm. At 

 the same time that this movement of straightening is made, a cur- 

 rent carries the granular protoplasm from the centre of the cytode 

 into the interior of the arm. This action repeated produces an 

 elongation of the arm, which is accompanied by a narrowing of its 

 basal portion and an accumulation of opaque granulations in its 

 terminal part. 



When the mobile arm has attained a certain length, it separates 

 from the body of the cj'tode, and moves like a Nematode worm. We 

 shall soon see what further transformations it undergoes. 



After this arm has separated and acquired an independent 

 existence, the other process follows the course of its development, 

 and arrives at the same state as the former one ; only for this 

 purpose it requires the whole remainder of the body of the cytode. 



If M. van Beneden has correctly coordinated the different phases 

 which he has been able to observe in the intestine of the lobster, 

 we must conclude that a single cytode gives origin successively to 

 two prolongations, each destined to become developed into a Grega- 

 rina : one separates from the body of the cytode, the other ab- 

 sorbs the rest of that body. 



These protoplasmic filaments, endowed with veiy active move- 

 ments, the author designates by the name oi pseudofilaricB ; he sup- 

 poses that it is their resemblance to j'oung Nematode worms which 

 has led certain authors to assume that the Gregarinm are a phase in 

 the evolution of the Nematoda. 



These pscudofilariee are thinned at one of their extremities, and 

 slightly inflated at the opposite (cephalic) extremity, which is always 

 strongly charged with refractive granules. After a certaki period 

 of activity their movements slacken ; the length of the body gra- 

 dually diminishes at the same time that its width increases, espe- 

 cially in the anteiior part. Then all movement ceases, and the 

 pseudofilaria remains motionless. Towards the middle of the body, 

 there appears a dark circular spot, formed by a material more 

 refractive than the protoplasm, and the limits of which become more 

 and more distinct ; this is the nucleolus. Around the nucleolus 

 there appears a transparent zone without granulations, the limits of 

 which are at first not very distinct, and Avhich becomes the nucleus 

 of the cell. The pseudofilaria shortens and becomes more or less 

 oval ; and an anterior projection or swelling, in which the refractive 

 granules have a tendency to accumulate, begins to be distinguish- 

 able. 



We have then before us a Grer/arina which has no longer any 

 important changes to undergo. It becomes elongated and acquires 

 more and more the form of a tube slightly dilated in its anterior 

 part. The posterior part becoming more elongated than the anterior, 

 the nucleus finally settles at the extremity of the anterior third of 

 the body. The refractive granules accumulated in the anterior 

 terminal inflection form a mass separated from the granular proto- 

 plasm of the rest of the body by a sort of transverse septum, formed 



