SOME OBSERVATIONS ON A NEW GREGAKINE. 277 



(fig-. 25 ft) stained very faintly with iron-hiematoxylin. They are 

 most obvious in cysts containing gametes or sporoblasts, and 

 have not been seen in the earlier cysts, at any rate in the same 

 form. Their size varies considerably, and they appear to be 

 products of the original karyosome which have lost most of 

 their staining properties, and which have become more obvious 

 owing to the splitting up of the protoplasm entailed in gamete 

 formation. The majority are rather too large to be referred to 

 the daughter-karyosomes. The main residue of the original 

 karyosome is often to be found, deeply stained, in these later 

 cysts. 



The gametes are very like those described for Lankes- 

 teria ascidige by Siedlecki (18), and show no signs of sexual 

 differentiation (fig. 26). Considering the fact that there is 

 at no time in the history of the encysted animals any difference 

 in structure, and that the nuclear changes are practically co- 

 incident, this isogamous type of gamete is what one would 

 expect. Conjugation has not been observed in the living 

 animal, owing to my studies being interrupted by my departure 

 from Heidelberg. Fig. 27 shows, however, what is practically 

 certain to be a zygote. The gametes measure about 3^, and 

 are roughly circular in outline. Their nuclei consist of small 

 masses of chromatin with no definite vesicular structure. 

 The zygote measured over 4'5 n, and contained two distinct 

 nuclei. Several cysts were found containing sporoblasts, 

 (figs. 28 to 33). These are ovoid bodies measuring 6 /x by 4 //, 

 and containing large vesicular nuclei. These sporoblasts gradu- 

 ally acquire a spore coat, and grow in size somewhat during 

 the process (6g. 33), so that in a cyst of sporoblasts one or 

 two may be detected with the outline of a formed spore (fig. 

 34). The fully formed spore is shown in fig. 35. The nuclear 

 changes resulting in the formation of the sporozoites have not 

 been made out, nor did I obtain a view of a free sporozoite. 

 It was easily seen, however, in optical sections of the living 

 spores that eight sporozoites were arranged peripherally 

 around a granular mass of residual protoplasm. The spores 

 measure 9 /.t by 7 n, and are uavicelliform, provided at each 

 end with a little peg-like projection (fig. 35). 



