288 E. A. MINCHIN. 



in an earlier stage there was one nucleus at each end of the 

 spore. Further, since these two nuclei must be derived from the 

 single nucleus of the sporoblast, we may piece together the 

 following history. Either before or after the assumption by 

 the sporoblast of the elongated shape of the spore, its nucleus 

 divides in two, the two halves going to opposite ends of the 

 spore. The two nuclei thus produced then each divide again 

 into two in a plane at right angles to their former plane of 

 division, so that we get the stage here described with four 

 nuclei, the protoplasm of the spore having in the meanwhile 

 secreted the cuticle and its appendages. It may be pointed 

 out in passing how much larger the nucleus of the sporoblast 

 is than that of the spore. 



3. Ripe spores were found in four cysts which were removed 

 attached to a blood-vessel and cut into sections (figs. 15, 16, 

 17, and 18). The external form of the spore and the struc- 

 ture and arrangement of its cuticle are the same as in the last 

 stage; but each spore now contains instead of four nuclei 

 eight sporozoites^ (falciform bodies). It is a little difficult in 

 studying the sections to be certain of the exact number, since 

 a spore might often be halved or partially removed, leaving 

 only a few of the sporozoites. Nevertheless, wherever an 

 uninjured spore could be satisfactorily observed, eight sporo- 

 zoites could be plainly made out, and in very many cases 

 where a spore was cut transversely eight sporozoites could 

 be seen (fig. 16, b) ; and it may, 1 think, be taken as certain 

 that this is the full and normal number in each spore. 



The sporozoites are exceedingly minute, and by no means 

 easy to make out. Nevertheless careful focussing with a 

 Zeiss's oil immersion 2*0 mm. showed them to consist of an 

 elongated darkly staining nucleus forming the head, to which 

 is attached at one end a delicate flame-like tail, doubtless 

 vibratile, and at the other end, which we may term anterior, a 

 minute conical point; but the latter structure was exceedingly 



1 Wolters uses the term " sporocysts " for what are here termed spores, 

 and "spores" for what I have used the name sporozoites. I have kept to 

 the nomenclature of Butsclili and Schneider. 



