GREGAKINIDJ3 85 



The chromatic contents of this nucleus now become very much 

 reduced. The nucleus breaks up and the first spindle is formed from 

 a minute quantity of the original chromatin. Numerous daughter- 

 nuclei are formed, the result of repeated mitotic division, and these 

 distribute themselves over the periphery of the parasite. The entire 

 organism becomes irregularly wavy in form, owing to the formation 

 of deep folds in its surface. Each nucleus surrounds itself with a 

 portion of the parent plasma, so that, finally, the entire organism splits 

 up into numerous pear-shaped female gametes which, formerly, were 

 regarded as sporoblasts. There is no residual body. The nuclear 

 changes differ slightly in the male gametocyte. They result in the 

 formation of numerous microgametes, which carry two free flagella 

 at their anterior end. These microgametes are long and narrow in 

 shape, those of Aggregata spinosa measuring 1 mm. in length, while 

 they rarely exceed O'OOo to 0'005 mm. in thickness. Fertilization has 

 not been directly observed. It is certain, however, that the process 

 of fertilization is followed by the encysting of the copula, which then 

 divides within the cyst into a varying number of sporozoites (three to 

 four in the varieties parasitic in Sepia, eight to twenty-four in those 

 found in Octopus). The ripe cysts containing spores are passed out 

 of the body of the octopus in the faeces, and the sporozoites are not 

 released until the cysts reach the intestine of a suitable species of crab. 

 The older notion that the spores were released within the gut of the 

 octopus has proved erroneous. 1 



The Aggregata are, for many reasons, a particularly interesting 

 group. They illustrate very clearly the necessity for extreme caution 

 in tracing out the developmental history of Protozoans. The descrip- 

 tions of the so-called Eucoccidium, which are to be found in all text- 

 books, are absolutely misleading because they are founded upon 

 insufficient and incorrect data. In spite of the care with which 

 Siedlecki conducted his investigations, they are yet incomplete in two 

 essential points. He was unable to observe directly either the process 

 of fertilization or the release of the sporozoite, and the gaps were filled 

 from the life-history of the Coccidia, with which class the organism 

 was at that time thought to have points of resemblance. 



Fresh material and cover-glass specimens should be prepared, and 

 sections in series will also be found very instructive. 



1 Th. Moroff, " Die bei den Cephalopoden vorkommenden Aggregata- Arten als 

 Grundlage einer kritischen Studie iiber die Physiologic des Zellkerns," Arch. f. 

 Protistenkunde, vol. xi, 1908, pp. 1-224; L. Leger et O. Dubosq, " L'E volution 

 schizogonique de 1' Aggregata (Eucoccidium) eberthi (Labbe)," ibid., vol. xii, 1908, 

 pp. 44-108. 



