THE WONDERS OF LIFE 



of plasm. He says that we must distinguish two chemi- 

 cally different kinds of plasm in living matter — the^ filar 

 (threadlike) and the inter-filar matter. The fine threads 

 of the former are of different lengths, and sometimes 

 run separately, at other times are bound in a sort 

 of net-work {mitoma and paramitomd). In certain 

 conditions of cell-life, especially in indirect cell-division, 

 these filar formations play a great part; and also in the 

 functions of highly differentiated cells, such as the 

 ganglionic cells. But in many cases these plasma 

 threads may be merely parts of a skeletal or frothy 

 structure (honeycomb walls in section). In any case, 

 we cannot regard the thread formation as a general 

 elementary structure of plasm; in my opinion, it is 

 always a secondary phyletic product of living matter, 

 and never a primary feature of it. 



Totally different from the three preceding theories of 

 the finer structure of the plasm is the granular theory of 

 Altmann (1890). He supposes that all living matter is 

 originally made up of tiny round granules, and that these 

 independently living hiohlgsts are the real "elementary 

 organisms," the microscopic ultimate individuals; hence 

 the cells which are formed by the combination of 

 these granules must be looked on as individuals of the 

 second order. Between the granules of the granulated 

 substance (the real active living matter) there is always 

 an inter-granular substance; the granules are regularly 

 distributed and arranged in these. The granules them- 

 selves, or the bioblasts, are homogeneous, sometimes 

 globular, and sometimes oval, or of other shapes. 

 However, the distinction between these substances is 

 quite arbitrary, and neither chemically nor morphologi- 

 cally well defined. Under the head of granules Altmann 

 throws together the most different contents of the cell — 

 fat granules, pigment granules, secretory granules, and 

 other products of metabolism. Hence his granular 



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