352 SUMMARY OF CUERENT RESEARCHES RELATING TO 



reticulately arranged ridges (Ceratium cornutum, and C. hirundinella, 

 Dinophysis), or the ridges do not form a network, but run more 

 irregularly, pores also appearing (Ceratium tripos, C. furca, C.fusus) ; 

 finally we fiud a division by bands into a number of plates of various 

 sizes with smaller intermediate striae, so that the plates show the 

 reticulated structure, the bands on the contrary being transversely 

 marked (Peridinium, Protoperidinium^ Diplopsalis) ; in Prorocentrum 

 (apparently) the membrane consists of two cuirasses, which are 

 perforated with fine jiores. 



The protop)lasni is apparently always sej^arated into ectoplasm and 

 endoplasm, which both show very varying differentiation. In the 

 cuirassed forms the ectoplasm is always quite structureless and homo- 

 geneous ; in Gymnodinium and Polyhrikos, the most highly developed 

 forms, it shows many peculiarities ; in G. gracile it is very much, 

 wrinkled and folded, and in G. spirals it contains muscular fibrillse 

 in its inner layers ; in Polyhrikos trichocysts are developed in it. The 

 endoplasm sometimes contains, at the same time, chlorophyll, and 

 diatomin and starch, or some similar amylaceous matter (^Ceratium, 

 Protoceraiium, Perid. tabula turn, Protoperid. Michaelis, Glenodiniiim, 

 Dinopjhysis acuta, Prorocentrwri), which indicates a mode of nutrition 

 similar to that of plants ; sometimes these substances are wanting, 

 and the body contains digested organisms (Gymnodinium, Polykrikos), 

 which indicates that alimentation takes place as in animals ; finaliy, 

 there seem to be some forms which are nourished neither by the 

 agency of chlorophyll (the assimilation of carbonic acid) nor by 

 animal matter, as we find in their endoplasm neither the above- 

 mentioned colouring matter nor foreign organisms (as in Protoperid. 

 pellucidum, Perid. divergens, Diplopsalis lenticula, Dinophysis loivis). 

 The endoplasm in Perid. divergens, Diplopsalis lenticula, &c., is 

 coloured slightly red ; in the former it usually contains little drops of 

 red-coloured oil. Wo contractile vesicle can be pointed out with 

 certainty. In all the forms in which the nutrition could not be seen 

 to be either assimilative or purely animal, a vesicle is found which 

 often communicates with the outer world through the flagellum- 

 furrow and a narrow canal, but is sometimes separated from it ; 

 probably its function is to take in sea-water (with nourishment). 



The nucleus is generally single ; only in Polykrikos we find four 

 (larger) nuclei. Those of the Dinifera consist of a fine granular 

 substance containing no nucleoli and colouring bright pink when 

 treated with picrocarmine (after alcohol). Only in Polykrikos is 

 there found a second sort of smaller nucleus (perhaps "primary 

 nucleus" in the same sense as in the Ciliata). The nucleus of 

 Prorocentrum still needs a closer examination. 



The locomotor apparatus, the special characteristic of the Cilio- 

 flagellata, consists of long, powerful flagella and smaller cilia. These 

 cilia spring either directly from the anterior end of the body (Proro- 

 centrum), or are arranged in one or two contractile rows in a transverse 

 furrow formed by two projecting plates or ridges (Dinifera). The 

 furrow lies either at the anterior extremity of the body (Dinophysis, 

 Amphidinium), or about the middle (the other forms) ; in Gymnodinium 



