No. 3.] THALASSEMA AND ZIRPHAEA. 587 



Methods. In both forms the material included stages fixed with picro- 

 acetic (i%-2% acetic acid), sublimate acetic (20%, 10%, and 3% acetic acid), 

 and pure sublimate. In general, the picro-acetic series gave the best results, 

 while in Zirphaea the pure sublimate was a complete failure. The eggs 

 were imbedded in paraffine cut into sections 2-1 o/i thick, mounted and 

 stained on the slide by various stains. For the achromatic structures, by 

 far the best results were obtained with iron haematoxylin, either alone or 

 followed by acid fuchsin, Congo red, orange, or eosin. For study of the 

 chromatin, the sections, after remaining in the haematoxylin for thirty-six 

 to forty-eight hours, were extracted until the cytoplasm became colorless, 

 and then restained with one of the plasma stains just mentioned. By this 

 method the chromosomes stand out conspicuously as intensely black bodies 

 upon a pale red or orange background. Their structure and changes can 

 then be traced with but little trouble. Good results were also obtained by 

 use of Flemming's triple stain and Auerbach's ('96) methyl-green acid- 

 fuchsin mixture. 



PART I. — THALASSEMA 



I. The Ovarian Egg and Nucleolus. 



The sexual products of Thalassema are developed, as Conn 

 ('86) has described, from the peritoneal covering of one of the 

 muscular bands about 5 mm. cephalad of the anus, and extend- 

 ing from the alimentary canal to the body wall. The ova and 

 sperm-cells very early become detached in masses from the 

 sexual glands, and undergo their subsequent development float- 

 ing freely in the body cavity. My studies upon the early ova 

 were made in large part from such masses imbedded and 

 sectioned by chance along with the earlier maturation stages. 

 These were not, however, in all cases to be relied upon, since 

 degeneration had, in many instances, already set in. More 

 satisfactory material was obtained by fixing the coelomic fluid, 

 whereby many such egg masses were obtained along with 

 innumerable coelomic corpuscles. 



The earliest clusters obtained consist entirely of minute cells 

 3/x in diameter, all possessing extremely little cytoplasm and 

 with nuclei in the spireme stage. After the segmentation 

 of the spireme into the reduced number of chromosomei; 

 {^iz., 12), the ovum commences to grow and all parts rapidly 

 increase in size, although the cytoplasmic growth is by far the 



