218 Proceedings of the Royal Physical Society. 
2. Formation of protoplasm around these nuclei into two types of 
cell, small with small nucleus, large with large nucleus. These 
two types of cell might be termed microcytes (Text-fig. 1, a) and 
megalocytes (Text-fig. 1, 0). 
3. Union of micro- and megalo- cyte to form the binucleate sporoblast 
(Text-fig. 1, ¢). | 
4. Union and fusion of two sporoblasts to form the four-nucleate pan- 
sporoblast (Text-fig.1, @), 3 and 4 may occur almost simultaneously. 
5. The two megalocyte nuclei divide repeatedly to form twelve nuclei 
(sixteen in forms with four polar capsules), while the two 
microcyte nuclei apparently remain as the two pansporoblast 
nuclei (Text-fig. 1, f and 9). 
Stages 3 and 4 have each been described by different observers, but 
always as being the only cell fusion which occurs. Thus it will be seen 
that the only new conception in this description of Myxosporidian spore 
development is the origin of the pansporoblast from four separate cells 
instead of from two, as according to previous authors. : 
It cannot be. said at present whether this form of development is 
universal for the disporous Myxosporidia, but the analysis of certain other 
accounts given above shows that there is no great difficulty in applying the 
same interpretations to some other forms. 
