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contributions are to be found in a paper of Plainer (17), according to 
whom the nutritive cells group themselves chiefly on the side of the 
egg-cells turned towards the walls of the acini. The nutritive cells very 
often lie in semicircular indentations of the cytoplasm of the egg- 
cells, and later migrate into the interior of them where they become 
digested. 
Obst’s (15) investigations confirm Pcatner’s observations in every 
respect. According to him the nutritive cells form a follicle about the 
ovum. The follicle cells lying at the side of the egg turned towards 
the wall of the acinus get into the interior of the egg-cell where they 
degenerate and become absorbed. 
So much is to be found in the literature as regards the supposed 
nutritive cells of the ova of the Molluscs. These data together with 
Obst’s figures got into such classic text-books as Wilson’s The Cell, 
and Korschelt-Heider’s Embryology of Invertebrates, and thus they 
become matters of common knowledge. 
My own observations made on some Pulmonates (Helix arbusto¬ 
rum , Succinea putris, Planorbis corneus , Limnaea stagnali#) and a 
Proso.branchiate (Neritina) led me, however, to the conclusion that in 
the case of the Gastropods we have not to do with a nutritive process, 
but on the contrary with a process of degeneration. 
At the beginning of my researches I also believed that the cells 
associated with the ovarian eggs were nutritive cells, but later it struck 
me that the egg-cells associated with the supposed nutritive cells were 
more or less degenerated: their outlines were uncertain, their cyto¬ 
plasm was decomposed, and not granular or filled with vitelline bodies, 
but it formed a peculiar fibrous-granular reticulate mass, their nucleus 
wrinkled, more or less dissolved, their chromatin disintegrated into 
larger or smaller granules, their nucleus and nucleolus were very often 
extremely large which, contrary to the nucleoli of the sound ones, had 
no chromatin at all, or if they had, the same was concentrated in a small 
part of the achromatic ground substance, and its quantity in compa¬ 
rison with the plastin (pyrenin) of the nucleolus was very small. 
The consideration of other phenomena led me also to the con¬ 
clusion that the greatest part of the egg-cells must somehow perish. 
The number of the egg-cells in the same stage of development — which 
therefore with the greatest probability ripen synchronously — is al¬ 
ways greater than that of the deposited ones, and this observation is 
in harmony with the other one, viz. that the degenerating egg-cells are 
always more numerous than the sound ones. 
I refer for further explication to fig. 1. Pl. YII which exhibits an 
