THE PAllASITE MINCHINIA. 451 



After some time has elapsed tlie gamete nuclei in the prozygote 

 approach one another (fig. 5 h) and fuse to form the syncaryon 

 (fig. 5 c). The zygote so formed ajDpears to be produced by 

 autogamy. Such may not be really the case, however, for it is 

 quite possible that the gamete nuclei may have been derived from 

 distinct parents. Either two plasmodia during their wanderings 

 may have come together and their cytoplasm fused before 

 encystment (plastogamy), or there is some evidence in other 

 Neosporidia to show that the amoebulse fuse in pairs on their 

 escape from the spore. In the latter case probably their nuclei 

 do not fuse but divide independently, and ultimately syngamy 

 takes place between gamete nuclei formed in equal numbers from 

 each parent. 



(3) Formation of sjyores. 



The zygotes generally proceed almost at once to divide twice 

 (PI. I. figs, 6 & 7) to give four sporoblasts : division is eflected 

 here again by a simple method of mitosis. As a rule, the nuclei 

 go through both their divisions before the cytoplasm divides, so 

 that the stage with four nuclei (PI. II. fig. 8) is quite common, 

 but sometimes division of the cytoplasm follows after the fiist 

 nuclear division . Also,these divisions are not ahvays simultaneous 

 even in one and the same cyst, thei'efore there may be enclosed 

 together with free sporoblasts masses with two, three, or four 

 nuclei, and even an undivided zygote. This fact added much to 

 the difiiculty of elucidating the life-history of Minchinia. 



The sporoblasts when first separated are very small and their 

 protoplasm rather vacuolar. They soon begin to secrete a mem- 

 brane which is produced into a short tail at either end (PI. II. 

 figs. 10 tt 1 1). The young spore then grows considerably : presum- 

 a,bly the membrane is so thin that it does not prevent the 

 absorption of food. While still quite small its nucleus divides, 

 giving off" a, parietal mass of chi'omatin (figs. 9« &, 9&) which 

 sometimes divides into two (fig. 9c) These parietal nuclei or 

 masses of chromatin, for possibly they are not true nuclei, are 

 very distinct at this stage. Their prominence, however, is very 

 transitory, for soon after they are masked by numerous other 

 chromatic bodies which are given out by the main nucleus. 

 Probably the parietal " nuclei " themselves also break down into 

 similar chromatic granules or globules. These are highly re- 

 fringent and pass to the peripheiy, where they arrange themselves 

 to form the chitinous spore coat, as will be more fully explained 

 later. 



At the stage when these globules are passing out in a centri- 

 fugal direction there arises in the cytoplasm, near the nucleus, a 

 homogeneous finely granular spherule (PI. II. fig. 14). I have 

 no evidence that this comes actually from the nucleus as described 

 by Granata (8) for Haplosportdmm limnodriU. The spherule is 

 distinguished by the fact that it stains only slightly and takes up 

 its position just underneath the ojoerculum. Unripe spores open 



