REMARKS ON THE STRUCTURE OF QREGARlNiE. 345 



Gregarinee, and that even if its muscular nature in this case 

 be admitted as probable, such a view does not do away with 

 the contractility of the typically contractile part of the 

 Gregarina — the cortical parenchyma. 



In the next place, it is necessary to make some remarks 

 upon the striations of the tunic recognised in various Gre- 

 garinse by various observers. In addition to his circular 

 transverse fibrillse, Van Beneden appears only to recognise 

 one source of striation, namely, " a passing state of the cor- 

 tical tunic," a temporary condition of contraction. 



To this cause he ascribes equally the longitudinal striations 

 observed by Lieberkuhn in large individuals of Monocystis 

 lumbrici) by Leidy in the cortical substance of the posterior 

 chamber in Gregarina blattarum, and subsequently by myself 

 in the fine proboscis-bearing Monocystis occurring in Jphro- 

 dite aculeata, as well as " the striations on the surface of the 

 body of a Gregarina from a Phyllodoce described by Clapa- 

 rede. The fibrillation which I described (' Quart. Journ. 

 Micro. Science/ vol. vi, p. 23) in the anterior expansion of 

 the cortical substance of Monoajstis nereidis he does not 

 mention (see fig. 2). 



Alexander Stuart, in a paper published in volume xv, No. 

 5, of the ' Bulletins of the Imperial Academy of St. Peters- 

 burg,' whilst describing two new Gregarinrc respectively from 

 the Ucteropod Pterotrachca and the Annelid, Telcpsavus, 

 gives his notions upon the subject of striation. He wrongly 

 cites my Monocystis Aphroditce as similar in form and mark- 

 ings to Claparede's Gregarina from Phyllodoce. It is, on the 

 contrary, very different, and he must, by an oversight, be 

 alluding under this name to my Monocystis serpulce, which is 

 similar to Clajiarede's species. Stuart sets down all stria- 

 tions in Gregarinida to the fibrillar structure of the cortical 

 substance, or '^ Muskelschlauch,''^ as he not inaj)propriately 

 terms it, and insists on the permanent character of the stria- 

 tions as a proof of their existence as structural elements. In 

 the cortical substance of M. tehpsavi he describes an outer 

 layer of excessively fine^ circularly disposed fibrillae, and an 

 inner series of more obvious longitudinally-disposed fibrillse. 

 Though he gives figures in illustration of his paper, Stuart 

 does not give any indication whatever of the circular stria- 

 tions in his drawings. If they exist, they undoubtedly are 

 evidence in favour of the contractile character of Van Bene- 

 den's circular coat. 



Stuart states that the longitudinal fibrillation is the more 

 obvious, and I may say that at the time that I observed 

 longitudinal fibrillation in the cortical substance of M. 



