BLOOD-PARASITES Ofc' FISHES OCCURRING AT ROVIGNO. 149 



are inclined to think the nuclei in some of his figures may be 

 possibly a trifle schematic both as regards the uniform size of 

 the granules and the rather suspicious regularity of the 

 reticulum ; but in many of the other figures there is, in our 

 opinion, an indication of the nuclear structure which is pro- 

 bably as correct as it is possible to obtain it by the 

 Romanowsky method. In none of Borner's figures is there 

 anything remotely resembling a karyosome, and, in fact, the 

 author expressly mentions that he never observed such a 

 structure in the nucleus.^ 



Numerous figures accompanying the description of new 

 hsemogregarines have been published during recent years, 

 all of them naturall}^ from Romanowsky preparations. It 

 would take too long to cite them ; nor is it necessary. It is 

 sufificient to say that in no case can the sti-uctural details of 

 the nucleus be deciphered. In all cases it is obvious that the 

 nucleus drawn was still hopelessly overloaded with stain. At 

 the best the nucleus is figured as a dense granular mass, 

 bearing often a strong resemblance to those in our figures 

 from Giemsa-stained preparations, from which it may be 



^ The only instance of which we are aware, where anything resembhng 

 a karyosomatic nucleus api^ears to be present, is in certain figures of 

 Wenyon's (22) on PL 12, purporting to represent H. gracilis in the 

 liver of Mabuia. The figures are from preparations stained by lisema- 

 toxylin. "We think it most likely that Wenyon has figured besides 

 phases of a hEemogregarine, also phases of a coccidian, the latter being 

 the ones in which the nuclei show a karyosome. His fig. 29 shows 

 undoubtedly the development of typical merozoites of a hsemogregarine 

 (cf . H. simondi) ; and it is only these merozoites which he figures also 

 in the red corirascles. His figs. 27, 22, and 31, on the other hand, we 

 consider, represent a Coccidian ; the two latter especially appear very 

 like young coccidian schizonts. Since our MS. was sent to the 

 printers the memoir by Halm (4b) has appeared. We can only point 

 out here that Hahn uses the term " karyosome '" in a sense quite 

 different from that in which we understand the word, namely, to mean 

 the entii-e nucleus when in a condition " devoid of visible chromatin 

 bodies " (p. 331). He terms such bodies '• achromatic nuclei " (which 

 seems to us rather a contradiction in terms), and calls them " karyo. 

 somes, in the sense that they are the bodies from which the chromatin 

 bodies subsequently arise." 



