82 Gaylord Swindle, 



drawing, Fig-. 11, on the opposite side makes clear such features 

 as the photograph has failed to reveal, because obliquity fails of 

 course to enter into consideration in drawing while the portion out 

 of focus is recorded in the photograph as a blurr at best. The 

 bipolar ganglion cell is marked, in addition to the stiff neurofibrillae 

 and a limited amount of Nissl substance, by the possession of a 

 nucleus strikingly similar to Fig. 1. A comparison of the tiny 

 chromatin granules with the neurofibrillae outside justifies in no 

 sense whatever the conclusion that the latter may have once upon 

 a time been in the same state of existence as the former. Such 

 would be momentarily a conclusion with both major and minor 

 premises lacking. The upper nucleus in the figure may however 

 be interpreted differently. Here we may begin to see how the 

 chromatin granules, through direct elongation in a given direction^ 

 may, in the general form of an irregular, continuous bundle, appar- 

 ently inclosed or not inclosed by a nuclear membrane — an in- 

 significant matter of course — be "squirted" forth from the nucleus 

 to assume a state of existence from one standpoint as independent 

 from the mother nucleus as a newborn S. maculosa from its parent. 

 We cannot, as in numerous cases, prove that it concerns itself in 

 this particular instance with a ganglion cell, for it possesses as yet 

 no nerve fibers. But its location, size, orientation, relation to neuro- 

 glia etc. are sufficiently strongly indicative of such as to place the 

 assumption within the bounds of logical consideration. Of course 

 proof of a sufficiently positive nature is at hand in only such 

 cases as are already marked by the presence of one or 

 more nerve fibers. But to be emphasized is a point of funda- 

 mental significance in explaining the origin of fi- 

 brillae outside the nucleus, in the cytoplasm, identi- 

 cal to a variable extent with nuclear material, but 

 chemically and morphologically different to the cyto- 

 plasm in which they are imbedded. The fate of many similar 

 nuclear products will be considered later under special topics. 



To resume the reference to concrete examples. Fig. 6, from the 

 outer grey matter of the spinal cord of S. maculosa, is an early 

 stage in the differentiation of chromofibrillae. In consideration of 

 the real beauty of this particular nucleus under proper conditions of 

 illumination and magnification it is to be regretted that its thickness,^ 

 together with its mai ked obliquity in position, exclude the possibility 

 of showing in the photograph more than a limited amount of the- 



