466 PROCEEDINGS OF THE ACADEMY OF [July, 



Chromatin Body No. 2. — This apparently consists of a nuclear mem- 

 brane, nuclear sap and chromatin which is typically in the form of 

 a rounded karyosome. The appearances, however, vary to a very 

 great extent. The chromatin is very often in the form of a rod (figs. 

 46, d, 7e, /, g). It may also consist of two or more separate bodies 

 (figs. 4c, lb, c, g, h). At times the chromatin mass is irregular in 

 shape, and appears to send out strands which unite with the mem- 

 brane (fig. 4e). In a large number of cases the membrane cannot be 

 demonstrated at all, the chromatic mass apparently lying free in the 

 cytoplasm (figs. 4c, lb, d, e, f, g). 



In iron hematoxylin the karyosome or karyosomes take a deep 

 chromatin stain and, as a rule, stand out sharply. With thionin or 

 Wright's stain the chromatin reaction is given, but the stain is pale. 

 This element obviously comes within the category of vesicular nuclei. 



Summarizing the above observations, it is seen that the spores of 

 Sarcocystis rileyi show two chromatic elements and two vacuoles. 

 The latter, although rather curious possessions, offer no difficulties 

 of interpretation. The young stages of certain haemogregarines (for 

 examples, Lankesterella and Karyolysus) typically show two vacuoles, 

 although it is not known what their function may be. 



It is not so easy, however, to explain the significance of these two 

 chromatic elements. The one, the chromatin body No. 1, is typically 

 a rounded solid element, belonging to the massive type of nucleus. 

 It takes an intense chromatin stain, and is clearly an element high in 

 nucleic acid. The other, chromatin body No. 2, consists of a nuclear 

 membrane, inclosing a clear space within which is one or more karyo- 

 somes. These stain like chromatin. This vesicular type of nucleus is 

 widespread in protozoa. 



With iron hematoxylin there is no choice between the staining 

 reactions of these two elements. Sometimes the one is more deeply 

 stained, sometimes the other, but in general both are black, and the 

 spores are seen at a glance to be binucleate. On the other hand, 

 with Wright's stain, chromatin body No. 1 is larger and more con- 

 spicuous than it is with iron hematoxylin, while chromatin body No. 2 

 may at first glance be overlooked. The appearance here is of a 

 uninucleated element. There is here very nicely illustrated the advan- 

 tage of the use of more than one staining method, and the contention 

 of the English School of protozoologists that iron-heematoxylin should 

 be used in the study of trypanosomes receives emphatic support. 



It is impossible to establish a correlation between the spores of 

 Sarcocystis rileyi and those of other Sarcosporidia. Concerning the 



