Februaet 1, 1907] 



SCIENCE 



193 



level from the others, or to accident. The 

 first of these possibilities is eliminated by side 

 views, which show that at full metaphase the 

 chromosomes lie in a flat plate; while the 

 early anaphases show the daughter chromo- 

 somes separating in two flat parallel plates. 

 The second possibility is, I think, wholly ex- 

 cluded in the case of Anasa by (1) the great 

 number of cells from different individuals that 

 show 21 chromosomes (often a smaller num- 

 ber, in my experience never in a single in- 

 stance 22) ; (2) the equally constant appear- 

 ance of 22 chromosomes in the female; and 

 above all (3) the fact that in Anasa and some 

 of the other genera the smaller number in the 

 male is shown hy the size relations to he con- 

 sistently owing to the absence of a particular 

 chromosome — in Protenor always one member 

 of the largest pair that appears in the female, 

 in Anasa always a member of one of the 

 largest two pairs. It is manifestly impossible 

 that this should be due to accident. As to 

 the passage of the lagging odd chromosome 

 without division to one pole in the second 

 division, I do not think the most critical ob- 

 server who examines the demonstrative evi- 

 dence given by very large numbers of cells in 

 my preparations can have the slightest doubt. 



I, therefore, think that as far as the first 

 three points are concerned, my results on 

 Anasa will sooner or later receive full con- 

 firmation at the hands of other observers. 

 Paulmier himself, after reexamining his own 

 preparations, was thoroughly convinced of his 

 error regarding the spermatogonial number — 

 an error that was a natural one at the time 

 his work was done. The most careful search 

 has failed to discover the original of the group 

 from which he figured 22 chromosomes, or any 

 other agreeing with it in number. Mont- 

 gomery's confirmation of my result as opposed 

 to his own earlier one is known. The con- 

 sistent and cumulative corroboration given by 

 so many other genera of Hemiptera (including 

 one of the Homoptera recently studied by Miss 

 "Stevens), some of them far more favorable 

 for study than Anasa, speaks for itself. 



Edmund B. Wilson 



Zoological Labokatort, 

 Columbia University, 

 January 20, 1907 



NOTES ON ORGANIC CEEMISTBT 

 DIAZONIUM PEROHLORATES 



The chemical activity of perchloric acid 

 and the fact that, under certain conditions, 

 it is explosive, are matters of common knowl- 

 edge, it is also generally known that many 

 of the diazonium (diazo) salts, such as ben- 

 zenediazonium nitrate, C5H5N iNNOj, are like- 

 wise explosive and their instability is often 

 very great. It might be anticipated, there- 

 fore, that diazonium perchlorates, if they 

 could exist at all, would prove to possess an 

 unusual degree of energy and that their study, 

 although it might be attended with danger, 

 would yield results of considerable general 

 interest. A number of such compounds have 

 recently been described, simultaneously, by D. 

 Vorlander,' and by K. A. Hofmann and H. 

 Arnold.'' The object of the former was to 

 endeavor to discover some basic substance 

 which, with perchloric acid, would form a 

 sparingly soluble salt that could be employed 

 instead of potassium perchlorate for the quan- 

 titative determination of the acid. This re- 

 sult has not been attained, but it is found that 

 an immediate, voluminous precipitate is 

 formed when phenylacridine sulphate is added 

 to a 1 per cent, perchloric acid solution, and 

 that a turbidity is produced when a 0.1 per 

 cent, solution of the acid is used. Hofmann 

 and Arnold desired to obtain some sparingly 

 soluble diazonium salts. The preparation of 

 henzenediazonium perchlorate, CjHjNiNClOj, 

 is very simple. Aniline (2 grams) is mixed, 

 at a temperature of 0°, with water (200 cc), 

 concentrated hydrochloric acid (6 cc), com- 

 mercial perchloric acid (10 cc) and sodium 

 nitrate (1.5 grams). The perchlorate imme- 

 diately crystallizes out in colorless needles, 

 which are strongly doubly refractive. Even 

 in the moist state this compound explodes 

 with great violence if rubbed or struck with 

 articles of stone or iron. When dry the ex- 

 plosive power of the substance is, of course, 

 very much greater. If a few centigrams are 

 dropped on blocks of hard wood, deep holes are 

 torn in them, but the explosion is so local in 

 its effect that vessels of thin glass, placed a 



'Ber. 39, 2713 (1906). 

 'Ibid., 39, 3146 (1906). 



