506 Wwconsin Academy of Sciences, Arts, and Letters. 



As before stated the process of cleavage may sliow a suc- 

 cession of stages from one end of a cell to another. Figures 

 26, 27, and 28 bring this out very clearly, since they are all 

 taken from the same cell at diffcTent regions thmrough its 

 length. The process of cleavage above described seems to go 

 on in its early stages at least, entirely independently of the 

 nuclei, but the result is al^vays, with an exception to be pres- 

 ently noted, the formation of uninucleate segments. In cells 

 in which the cleava^re phones cut between recentlv divided nu- 

 clei, so that the nuclei lie quite close to the cleft, the nuclei 

 frequently have the elongated pointed shape previously de- 

 scribed. (Figs. 28, 30.) The smaller end of tlie nucleus lies 

 nearest the cleavage plane. In some cases a distinct granule 

 can be seen Ivinc: next to the newlv formed membrane at the 

 point nearest tlie smaller end of the nucleus. Whether this 

 granule has anv special significance could not l>e determined. 

 Its occurrence is by no means constant, and the cases where it 

 w^as obser\^ed are quite possibly accidental ones, the granule 

 itself being but one of tlie numeroiLS small bodies frequently 

 found in other parts of the cytoplasm as well. 



When the cleavage has reached the uninucleate stage the 

 segments begin to separate from one another and to round up 

 into distinct bodies. The sides of the cleavao:e furrows are 

 drawn away from each other so as to leave between them irreg- 

 ular quite broad clefts through the protoplasm. (Fig. 30.) 

 So far as I have observed the clefts do not usually appear un- 

 til the uninucleate stage is reached, but in some cases the sepa- 

 ration may take place before cleavage is complete wdtli the re- 

 sult that large binucleate masses form spores directly. In 

 these spores there is a pair of cilia connected with each nu- 

 cleus. (Fig. 39.) These giant spores were, as previously 

 stated, observed by Eraun and his conclusion that they repre- 

 sent cases of incomplete cleavage is undoubtedly correct. 

 The clefts thus produced are perhaps what Klebs thought were 

 intraplasmic vacuoles, and it is quite possible that he failed to 

 see the earlier stages showing the cleavage furrows first 

 formed. It would certainly be very easy to overlook 

 such stages in matenal poorly fixed and stained and viewed 

 only from the surface of the entire cell. 



