102 The Individual Tracks 



vices to the organism in this Hfeless condition, and form 

 the extreme instance of a reduction on the somatic tracks. 



But there are also cases of a lesser reduction. Fre- 

 quently, in the Algae, as Schmitz describes, *'In the in- 

 terior of the cells, the chromatophores, of which there is 

 no longer any need, and which, in the economy of the 

 whole plant, were equipped and adapted exclusively for a 

 definite single function, disappear."^^ Especially is this 

 often the case in complexly organized and highly differ- 

 entiated algae. Sometimes, as it would seem, in the in- 

 most tissue-cells, but most commonly in the hairs and 

 rhizoids. 



A further instructive instance is given by the spore- 

 sacs of the Ascomycetae. In these flask-like cells there 

 originate, through the division of the nucleus, the nuclei 

 for the individual spores, while the mother-cell, according 

 to the available data, does not retain any nucleus. When 

 the spores are formed the mother-cell has, therefore, be- 

 come a non-nucleated protoplast, although it has by no 

 means completed its life-task, since it has still to take a 

 very active part in the extruding of the spores, for which 

 purpose it must retain, in the interior of its numerous 

 vacuoles, the necessary osmotic pressure. 



In our cell-pedigrees the ripe ascus forms the last 

 somatic twig of the germ-track which culminates in its 

 spores. This twig is simple, i. e., it does not necessarily 

 branch further. What lends importance to this illustra- 

 tion, however, is the present conception of the significance 

 of the nucleus. For, if it is the seat of the latent hered- 

 itary characters, we may assume that these are lacking 

 in the ripe ascus. And evidently the latter does not need 



i^Schmitz, Die Chromatophoren der Algen. p. 137. 1882. 



