152 Edward Hindle 



contains a fine meshwork of chromatin together with a deeply stain- 

 ing nucleolus. The latter usually contains numerous vacuoles, and 

 is not a mere aggregation of chromatin. 



Internal Changes after Treatment with Butyric Acid. 



After the membrane formation is complete the cytoplasmic 

 granules hecome aggregated together in clumps and therefore the 

 protoplasm loses its regular appearance. 



A few minutes later the nucleolus shows unmistakable signs of 

 dissolution, as it stains much more lightly, and may even break 

 down into two or more smaller ones (Fig. 2,^). Meanwhile the granules 

 in the vicinity of the nucleus disappear, and thus it becomes sur- 

 rounded by a clear zone, from which faint radiations extend into 

 the cytoplasm (Fig. 2). 



Certain of the granules immediately surrounding this region stain 

 much more deeply than others (Fig. 2, ch.gr.). Probably this ap- 

 pearance is due to the formation of acids, as a result of oxidation 

 processes starting from the nucleus and extending out into the cyto- 

 plasm, and LOEB ('06) has shown that acids are formed in develop- 

 ing eggs. 



This is succeeded by a rapid growth of the nucleus which in 

 some cases increases to as much as three times its original diameter. 

 The chromatin then aggregates together and assumes the form of a 

 spireme which subsequently breaks up into 18 chromosomes. 



In eggs that are developing at ordinary temperatures, about two 

 hours after treatment with butyric acid very distinct astral rays appear, 

 extending radially from the now indistinct nuclear membrane into 

 the cytoplasm and apparently centring in the nucleus. This radiation 

 does not usually resolve itself into a bipolar figure but persists as 

 a monaster. Frequently the chromosomes divide and become drawn 

 out along the rays so as to appear scattered throughout the cyto- 

 plasm (Fig. 14). This may be succeeded by a reduction of the rays 

 and a reconstruction of the nucleus with an increased number of 

 chromosomes. A redevelopment of the monaster may now follow and 

 the whole series of processes be repeated two or three times. The 

 changes observed agree, therefore, with WILSON'S description of the 

 behaviour of monasters in eggs that have been treated with mag- 

 nesium chloride ( WILSON, '01). Within 2 or 3 hours these eggs be- 

 gin to degenerate by a process of cytolysis (Fig. 13), by means of 



