334 w - E - HOY, JR. 



there are 44 chromosomes. This includes eight macro- and four 

 w-chromosomes. He concludes, therefore, that a division of 

 the chromosomes had taken place without a subsequent division 

 of the cell body, and further states that such a condition is not 

 uncommon in the investing cells of the ovary, of the oviduct, 

 and of the fat body. These cells are considered by him as either 

 degenerating or as highly specialized. 



Morrill ('10) figures "incomplete blastoderm" mitoses in the 

 developing eggs of Anasa, and finds that there are two kinds of 

 embryos with respect to their chromosome content, one contain- 

 ing 21, and the other 22 chromosomes. The two different chro- 

 mosome groups correspond, respectively, to the groups found in 

 the spermatogonia and the oogonia, showing the same size 

 differences and the same number of the various types of chromo- 

 somes. He also reports one case of 23 chromosomes, but suggests 

 that this is due to an accident in technique. 



The results presented in the present paper were obtained from 

 several stages in the developmental history of Anasa. These 

 stages can be grouped, roughly, under three heads: I. Late 

 cleavage (pre-blastodermic) and early blastodermic; II. Appear- 

 ance of the limb buds, and first indications of segmentation in 

 the embryo; III. Shortening of the elongate embryo. Of these 

 stages, stage I. shows the clearest and most diagrammatic chro- 

 mosome plates. The second stage shows division figures in the 

 undifferentiated ectoderm, and stage III. was excellent for mitotic 

 figures in neuroblasts, the mesoderm, and the hypodermis. 



In these stages over 100 counts were made of equatorial or pre- 

 equatorial plates. The difficulties first experienced were stated 

 in a preliminary paper (Hoy, '14), as was also the explanation of 

 some plates apparently containing an atypical number of chromo- 

 somes. It must be borne in mind that in some cases there 

 appears to be a diversity in the chromosome number of different 

 cells, but in all these plates the chromosomes are crowded 

 together making an enumeration extremely difficult. However, 

 there seems to be no case where an explanation of an apparently 

 aberrant number cannot be made, logically and clearly, on the 

 grounds of accidents in technique, overlapping of the chromo- 

 somes, or apparent fusion of several chromosomes due to poor 



