CHROMATOID BODY IX PENTATOMA. 403 



among them, or at the spindle poles extruded nucleoli or nu- 

 cleolar fragments, chromatoid bodies, "acrosomes," yolk-gran- 

 ules, or the like but one can not avoid the suspicion that some 

 of the existing contradictions in the literature may have arisen 

 from some such source. Many cases might be cited in illustra- 

 tion of the danger of such confusion. I suggest, for instance, a 

 comparison of my Figs. 9, 10, 22, 23 of Pentatoma (first and second 

 division) with Stevens's Fig. 5 of the first division of Ceuthophihis 

 ('12), the same author's Fig. 71 of Stenopelmatus ('05), Morse's 

 Fig. 46 of Periplaneta ('09), and Duesberg's Fig. 45 of the rat 

 ('08). In all of these cases a compact, more or less deeply 

 stained, spheroidal body is seen near one pole in the telophases or 

 late anaphases, lying near the chromosome-group; and the simi- 

 larity is increased by the fact that in the first three of these 

 cases this body is surrounded by a clear, vacuole-like space. So 

 deceptive is this resemblance that any observer without careful 

 study might readily conclude that the body in question is in 

 each case an accessory chromosome; yet in only two of the five 

 cases would this conclusion be correct. In Pentatoma and the 

 rat this body is of protoplasmic origin (chromatoid body), in 

 Periplaneta, according to Morse, an extruded nucleolus (plasma- 

 some) . Only in Ceuthophilus and Stenopelmatus, if Miss Stevens's 

 conclusions were correct (I have no reason to doubt that they 

 were) is this body an accessory chromosome. 



Such facts make it clear that the presence of sex-chromosomes 

 can not safely be inferred alone from the presence of chromosome- 

 like bodies lagging on the spermatocyte-spindles, or lying near 

 one pole. The presence of compact, deeply staining nucleoli 

 during the growth-period is by itself equally indecisive. In some 

 cases the "plasmasome," especially after certain fixatives such 

 as Bouin's fluid, may stain quite as intensely as the chromosome- 

 nucleoli with haematoxylin, safranin and other dyes (cf. Gutherz, 

 '12). Decisive evidence regarding these bodies can only be 

 obtained by tracing their individual history and by accurate 

 correlation of the chromosome-numbers in the spermatogonial 

 and spermatocyte-divisions. It hardly need be added that great 

 caution is necessary in dealing with difficult material in which 

 for any reason such a test can not be completely carried out. 



COLUMBIA UNIVERSITY, February 19, 1913. 



