32 



on cell divisions in seed-buds of Epipactis palustris. Probably in 

 direct relation to this eccentric manner of cell division are the 

 facts, that the separating wall is generally thicker at the base 

 than at the top, and that both halves, the chloroplast has already 

 divided into before, diverge more on the side where the separa- 

 ting wall will start (or started) than on the opposite side (Fig. 17a^ — c, 

 18, 29). In the one case of concentric division which I observed 

 these phenomena, accordingly, did not occur (Fig. 25). 



3. I want to mention a phenomenon that is only to be seen 

 on very accurate observation. From the apical end of the sepa- 

 rating wall, when growing, a very thin line is extended to each 

 of both halves of the chloroplast (Fig. 26 — ^29). These lines are 

 thinner than the separating wall itself, and evidently move on 

 through the whole cell with the growth of this wall. In con- 

 nection with the facts in Spirogyra, one might be inclined to 

 consider these lines as threads of the nuclear spindle ; which 

 spindle will then move from one side of the cell-wall to the 

 other, according as its forming of the separating wall proceeds; 

 therefore, something like Treub stated in Epipactis, But I can 

 not say this for certain, for I don't possess any observations as 

 to the nuclear division. 



4. When studying these stages of the algae in division, one 

 should take care not to confound simple figures caused by the 

 diffraction of the light with real cell structures ; one is apt of 

 doing this on account of the very small dimensions of the chlo- 

 rophyll corpuscles. These figures, however, are easily to be re- 

 cognized, as they are always parallel to the cell-wall or outline 

 of chloroplast. 



5. I could never detect any trace of a membrane 

 surrounding — as if it were a mother -cell-wall — 

 a stage of division as for instance Fig. 20, 22 and 27 show; 

 although I have always accurately examined. 



The chlorophyll corpuscles in the amoebocytes are nearly al- 

 ways turning slowly; one time one can observe such an alga 

 from this side, next from that side; a thing of much importance 

 when studying stages of division. In this way the following 



