Dr Barry on Fissiparous Generation. 217 



ing to periods in the life of ordinary cells. Thus in Ehrenberg's 

 Monadina are to be found, I think, the following objects : 



1. Globules and discs. 



2. Discs with a pellucid point. 



3. The pellucid part dividing. 



4. Nucleated cells. 



5. The nucleus dividing, and thus giving origin to, 



6. Young cells, which are seen both within and escaped 

 from parent cells. 



62. The same family, the Monadina, present also ciliated 

 discs, — ^the discs being either single, or in groups radiating 

 from a centre. 



63. In 1840, I communicated to the Society the fact, that I 

 had found blood- corpuscles revolving; and in 1841, delineated in 

 another memoir the cilia, by means of which this takes place.* 

 These cilia, sometimes presented by the star-like blood-cor- 

 puscle, are the elongated discs into which its nucleus or hya- 

 line divides. 



64. My observations on Spermatozoa, also communicated 

 in 1841, shewed them to arise in the same manner. 



65. It is not meant that the discs simply become sharp- 

 pointed or elongated. So far from this, the process is very 

 elaborate. There takes place division and sub-division, so as 

 to produce extremely minute discs, which coalesce to form the 

 cilia. My belief is, that it is by globules of the pellucid sub- 

 stance, so constantly referred to in this memoir — the hyaline 

 — that cilia of every kind are formed ; the globules first pass- 

 ing into discs in the manner above described (par. 15). 



QQ. How striking the resemblance between some sperma- 

 tozoa (fig. 1) and the ciliated discs in Ehrenberg's Pandorina ! 

 (fig. 6). The spermatozoa, as just stated, arise from division 

 of the nucleus of a cell, i, e. from division of the hyaline ; 

 and I think it is scarcely less obvious that the ciliated discs of 

 the Pandorina have the same mode of origin. 



67. Membrane is formed by the same means as those pro- 

 ducing cilia, namely, by division and sub-division into ex- 



* Phil. Trans. 1841, Plate XXII. figs. 104, 105. p. 226, par. 124. It was stated 

 that the examination was made, in one instance, 18 hours, and in the other, two 

 days after death. 



