294 Dr. W. Plnngsheim on the Germination 



small, irregular starch-granules, coloured blue by iodine (PI. IX. 

 fig. 8 i, i), around which could often be detected an enveloping 

 coat, the membrane of the dead spore. The spore-mother-cell 

 from which the moving spore has escaped (fig. 8 k, k, I), only 

 changes so far that the yellow-brown nucleus lying in it acquires 

 a regular outline and an indistinct structure. The orifice through 

 which the moving spore has escaped, may still always be distin- 

 guished in the membrane of the mother-cell, if its position is not too 

 unfavourable (fig. 8 ^, k, I, I). The spore-mother-cells exactly 

 resemble those structures which I had found in the conjugated 

 cells of old filaments (PI. VIII. fig. 4*). )^ 



I have met with the following inessential variations from ordi- 

 nary course of formation of the moving spores in the spore- 

 mother-cells just described. Frequently several mo\'ing spores 

 are formed, instead of one, in a spore-mother-cell, and this is the 

 cause of the variable size of the spores. Moreover, one or more 

 little brown corpuscles — portions of the central brown-yellow 

 nucleus of the spore-mother-cell — are often combined with th'^ 

 finely granular mucilage which collects in the spore-mother-ceH" 

 for the formation of the spores. In such cases the free spore 

 likewise possesses one or more brown-yellow nuclei. Finally,^ 

 the finely granular mucilage inside the spore-mother-cell fre- 

 quently never arrives at the formation of the spore, but is tran^-' 

 formed at once into starch-granules (PI. IX. fig. 8 m). ' '\'[ 



The question now arising, how we are to interpret these moving 

 structures, it appears to me that their mode of formation and the 

 regularity of their appearance necessarily repel the idea that 

 they are accidental, abnormal productions, without further value 

 in the development of the plant. That they are foreign struc- 

 tures, not belonging to the Spirogyra, would be an altogether 

 inadmissible hypothesis, since they are formed in the interior of 

 the closed filament-cells of the Spirogyi-ae, directly from their con- 

 tents; for how, supposing them to be Infusoria, should ari 

 earlier generation of them have come into a closed cell ? or is it 

 probable that such Infusoria, produced by a generatio aquivoca, 

 would begin and end their life in the interior of a vegetable cell f 



In my opinion the most direct and simplest assumption, in 

 the present condition of science, is, that they are propagative^ 

 cells of the Spirogyrce, capable of development, and if set free,' 

 under favourable circumstances, from the filament-cell during 

 their motion, they would reproduce the parent plant. ' 



* When I drew fig. 4, 1 was still unacquainted with the history of deve- 

 lopment of this cell, and overlooked the orifices in the outer membrane; 

 through which the moving spore had emerged. Subsequently, however, , 

 J could in every case see these orifices most distinctly in these cells,. aho^ 

 occurring in the conjugated cells of old filaments. n^y^v.- 



