86 THE ROYAL SOCIETY OF CANADA 



conducted in the laboratory over the microscopic field. I would 

 therefore gladly welcome to my Department any investigator who is 

 anxious for an interchange of views on this intricate and very perplexing 

 subject. 



Fig. 5 is from another specimen showing a shrunken nucleus in 

 the act of discharging its achromatic material, which is seen to form 

 a well defined oval area extending from the upper nuclear pole. Two 

 other nuclei in the same field exhibit the turgid condition, which 

 exists previous to discharge. They are thus in striking contrast to 

 the shrunken one. In Fig. 2, a, a' and b, b', show respectively turgid 

 and collapsed nuclei, while in Fig. 6 is exhibited the largest turgid 

 nucleus discovered during these investigations. Fig. 7, is an extra- 

 ordinary specimen for it shows two nuclei which had become so 

 distended with achromatic material that they had actually distorted 

 the course of a neighbouring bundle of muscle fibrils. This last 

 figure is likewise very instructive as a proof of the continuance of the 

 discharge of this nuclear achromatic material even when the develop- 

 ment of the muscle fibres has reached a fairly advanced stage. It is 

 more difficult to demonstrate the persistence of this remarkable 

 nuclear ^discharge in the later phases, owing to the gradual displace- 

 ment of the nuclei by the developing muscle fibres. Indirect evidence 

 of its existence is, however, furnished by the fact that as striation 

 advances there is a simultaneous increase in the amount of the sur- 

 rounding undifferentiated sarcoplasm. In this way, a steady and 

 progressive expansion in the size of the individual muscle fibres is 

 amply provided for. 



The extraordinary behaviour of the nuclei of the myosyncytium 

 just chronicled confirms in several respects the observations of Macal- 

 lum^ and Eyclesheimer- on the nuclei of the striated muscle fibres in 

 Necturus lateralis, and is probably the chief explanation of the so- 

 called degenerative changes in developing striated muscle described 

 by Godlewski,^ Mayer,^ Barfurth,^ and Bardeen,^ and referred to in 

 Part II of this memoir. For example, Godlewski describes the proto- 

 plasm as becoming more homogeneous, and collected round the 

 nuclei, while some of the fibrils break up and disappear. This observer 

 further states that the nuclei become "pale and poor in chromatin," 

 while in some forms of degeneration the muscle "cells" become vacuo- 

 lated. All biologists are ready to admit that growth and decay are 

 frequently quite closely associated conditions. It is therefore possible 

 that some of the phenomena described above may be explained as 

 minor degenerative changes. However, as a result of my researches 

 the following may also be suggested as possible explanations of these 

 ', ^, ^, ^, ■', and ^ op cit. 



