of Some Embryo-sacs. 85 



seen that the chromosomes are composed of a number of 

 quite evident granules. This granular structure of the 

 chromatin cannot be seen in the later stages of mitosis. 



The nucleoli vary in number from one to as many as three 

 in Scilla or seven in Lilmm. The nucleoli are quite frequently 

 surrounded by a clear zone filled with nuclear sap. The 

 nucleolus has a dense homogeneous appearance and in Liliitin 

 may exhibit a number of small yellowish oil-like bodies 

 embedded in its substance. In preparations stained with a 

 single stain like Delafield's Haematoxylin the nucleolus stains 

 much more deeply than the chromatin. If sections stained in 

 Haematoxylin be now stained in Eosin the nucleoli become red 

 while the chromatin still remains blue. This would indicate 

 that the nucleoli are of a different chemical nature from the 

 chromatin, since they readily part with one stain for another. 

 The chromatin holds stains tenaciously. Hence if the 

 nucleolus was simply a very condensed mass of the chroma- 

 tin, we would expect that chromatin would the sooner part 

 with its Haematoxjlin for the Eosin. Such, however, is the 

 reverse of what happens. 



In some studies of mitosis in the Basidiomycetes, Wager 

 describes the nucleolus as becoming smaller in size and the 

 chromosomes increasing in size in proportion as the nucleolus 

 becomes smaller. The nucleolus takes on a fainter stain as it 

 becomes smaller ; while the chromosomes, which originally 

 stained differently from the nucleolus, now take on the same 

 staining properties as the nucleolus originally possessed. He 

 accordingly comes to the conclusion that the nucleolus is 

 probably similar in nature to the chromatin. I have failed to 

 observe anything which would tend to confirm this view. 



The centrosome question, as far as the Spermatophyta go, 

 seems almost as far from solution as ever. Since Guignard 

 first described centrosomes in Liliiim Martagoii, quite a number 

 of workers have applied themselves to this problem. One of the 

 most recent papers is that by Mottier on Lilium and Podophyllum. 



