SMALL wood: maturation of haminea solitaria. 275 



and that in the germinative vesicle of Haminea, as the basichromatin de- 

 creases, the oxychromatin becomes more abundant. During the growth 

 of the ovum until maturation begins, there is a gradual decrease in the 

 amount of material which takes a basic stain. The first thing to form 

 in the early maturation figure is a linin network. Upon this network 

 there are gradually formed small masses of chromatin. The linin net- 

 work and the masses of chromatin give rise to the chromosomes. Since, 

 then, there is a stage where there is little or no visible chromatin, one 

 must conclude that the chromatin passes through a non-staining condi- 

 tion, — probably, as Wilson maintains, a liquid condition, — and that 

 it is re-collected in the chromosomal vesicles, where it again takes a basic 

 stain. 



The investigations in experimental cytology have yielded many new 

 facts during the past few years, and the results are in many cases 

 directly comparable with those following the normal activity of the egg. 

 If these results are to be of perrnanent value and" are to help in estab- 

 lishing general laws, they should be verified under conditions as far as 

 possible normal. Haminea seems to me to afford confirmation of the 

 results obtained by experimentation in regard to the liquid and non- 

 stainable condition of the material which is to become the chromosomes. 

 Here we have a perfectly normal process, taking place under natural 

 conditions, which is in a measure parallel to the experimental results. 

 The results, found under both normal and experimental conditions, 

 make it probable that the persistent individuality of the chromosomes 

 is not of universal occurrence ; in Haminea the chromosomes do not 

 have any connection with a spireme. This fact is interesting because 

 of the significance that has been attached to spireme formation as noted 

 in the passages quoted. We are hardly justified in drawing any radical 

 conclusions from this one case, clear as it is. It does suggest, however, 

 that the question is still open, and that one needs more observations 

 before admitting as universal the occurrence of a spireme, and before 

 accepting the supposed significance of its division as a definitely estab- 

 lished universal fact. 



(b) After Deposition. 



(L) First Matcration Figure. 



In the interpretation and nomenclature of the centrosome in a former 

 paper I (Smallwood, :0l) followed Conklin's (:0l) use of the terms of 

 Van Beneden et Xeyt ('87). Since that time has appeared the extended 



VOL. XLV. — NO. 4 2 



