NUCLEOLI IN EUSCHISTUS* VARIOLARIUS. 2 I/ 



more chromatin nucleoli, by counting 625 cells in one testis, and 

 of these cells 591 showed one nucleolus, 27 two nucleoli, and 7 

 three nucleoli. These 625 cells represented only a small area of 

 the preparation and we did not repeat the experiment on another 

 testis the estimate, therefore, offers merely an indication that in 

 a large majority of cases only one chromatin nucleolus is present. 



By a comparative study of the spermatocytes and oocytes of 

 the same form we ought to find an answer to the question, 

 whether the chromatin nucleolus is associated with the male cell 

 only, or whether it has its origin in the oocyte. 



As far as we are aware, the germinal vesicles shown in Plates 

 I., II. and III. are the first that have been demonstrated in any of 

 the Hemiptera heteroptera. A great deal has been written about 

 the spermotocytes and important generalizations have been drawn 

 from the behavior of the chromatin nucleolus in these male cells, 

 but not one word has been said about the corresponding, very im- 

 portant stages in the female, although we have been confidently 

 assured that the chromatin nucleolus in the male has been derived 

 from the egg. If this is true, it would seem at least logical to 

 expect to find some evidence of its presence in the egg at the 

 stage of development corresponding to the stage in which it is so 

 conspicuous in the male cell. 



Even if we assume for the sake of argument that the chromatin 

 nucleolus is a chromosome, we still do not avoid the logical ex- 

 pectation of finding it in the oocytes, for if one of the chromo- 

 somes of the spermatocyte possesses the distinguishing trait of 

 persisting through the rest stage in the form of a chromosome 

 nucleolus, and if that chromosome is a chromosome contributed 

 to the male cells from the mother, we should expect to see its 

 distinguishing characteristic manifested in even a more marked 

 degree in the oocyte. And further, as the chromosome nucleolus 

 of the spermatocyte is claimed to be only one of a pair of chromo- 

 somes --its mate being contributed by the egg at the time of 

 fertilization -- we should expect to find in the resting oocyte a 

 pair of chromosomes represented by two univalent, or one biva- 

 lent chromosome nucleolus. 



In the case of Enschistus we are told that the larger of the two 

 chromatin nucleoli of the spermatocyte is the homologue of the 



